1001-00004 · Ardent Capital Partners · Closing

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CONFIDENTIAL

CALDERWOOD & HARKNESS LLP 7 Times Square New York, NY 10036 Tel: (212) 558-4000

Fax: (212) 558-3588

www.calderwoodharkness.com

[__], 2025

VIA EMAIL AND OVERNIGHT COURIER

Luminex Systems Holdings Inc. 2100 Reston Gateway Drive, Suite 800 Reston, VA 20191

Attn: Annelise Gruber, Chief Financial Officer

With copies to:

Ridgeline Growth Equity Fund II LP 200 Clarendon Street, 52nd Floor Boston, MA 02116

Attn: Jonathan Ashford, Managing Partner

Meridian Venture Partners IV LP 600 Montgomery Street, Suite 2800 San Francisco, CA 94111

Attn: Claire Fujimoto, Managing Partner

Caldwell, Raines & Sheppard LLP 51 West 52nd Street New York, NY 10019

Attn: Patricia Okonkwo / Daniel Feinberg

Atlas Shareholder Services Inc. 6201 15th Avenue Brooklyn, NY 11219

Attn: Dennis Carmichael

Re: Acquisition of Luminex Systems Holdings Inc. — Request for IRS Form W-9 / W-8BEN / W-8BEN-E Agreement and Plan of Merger, dated as of March 24, 2025, by and among Ardent Apex Holdings Inc., Ardent Apex Merger Sub Inc., and Luminex Systems Holdings Inc. Calderwood & Harkness LLP Matter No. 1001-00004

Dear Ms. Gruber and Selling Stockholders:

1. Introduction and Purpose

Calderwood & Harkness LLP serves as legal counsel to Ardent Capital Partners III LP (the "Buyer" or "Sponsor") in connection with the pending acquisition of Luminex Systems Holdings Inc. (the "Company" or the "Target") pursuant to the Agreement and Plan of Merger, dated as of March 24, 2025 (as the same may be amended, supplemented, or otherwise modified from time to time, the "Merger Agreement"), by and among Ardent Apex Holdings Inc., a Delaware corporation ("Parent"), Ardent Apex Merger Sub Inc., a Delaware corporation and wholly owned subsidiary of Parent ("Merger Sub"), and the Company.

As you are aware, the Merger Agreement provides for a reverse triangular merger pursuant to which Merger Sub will merge with and into the Company (the "Merger"), with the Company surviving the Merger as a wholly owned subsidiary of Parent (the "Surviving Corporation"). At the effective time of the Merger (the "Effective Time"), each share of common stock, par value $0.001 per share, of the Company ("Company Common Stock") issued and outstanding immediately prior to the Effective Time (other than shares held by Parent, Merger Sub, or the Company (as treasury shares), and other than dissenting shares and management rollover shares) will be converted into the right to receive $20.00 per share in cash, without interest (the "Per Share Merger Consideration"). On a fully diluted basis, the aggregate Merger consideration (the "Aggregate Merger Consideration") is approximately $2,800,000,000 (two billion eight hundred million dollars), representing $20.00 per share across 140,000,000 fully diluted shares of Company Common Stock, payable in cash (except for management rollover equity, which is subject to separate rollover agreements).

The purpose of this letter is to request that the Company and each selling stockholder of the Company provide completed Internal Revenue Service ("IRS") tax certification forms in advance of the anticipated closing of the Merger. In connection with the payment of the Merger consideration at closing, United States federal tax law requires the Buyer (through the paying agent, Atlas Shareholder Services Inc. (the "Paying Agent")) to collect taxpayer identification information from each payee in order to comply with the information reporting and backup withholding obligations imposed by the Internal Revenue Code of 1986, as amended (the "Code"), and the regulations promulgated thereunder (the "Treasury Regulations"). This letter describes the specific forms required, the legal basis for the request, and the consequences of failing to provide the requested certifications.

We respectfully request your prompt attention to this matter, as the timely collection of the forms described herein is essential to ensuring that the closing of the Merger proceeds on schedule and that the payment of the Merger consideration to the selling stockholders is not subject to unnecessary withholding or delay.

2. Legal Basis for This Request

The request set forth in this letter is made pursuant to, and in furtherance of compliance with, the following provisions of federal tax law:

(a) Backup Withholding — Section 3406 of the Code. Under Section 3406 of the Code, the Paying Agent is required to deduct and withhold a tax (commonly referred to as "backup withholding") at the then-applicable statutory rate (currently 24%) from certain "reportable payments" made to a payee if (i) the payee fails to furnish its correct taxpayer identification number ("TIN") to the Paying Agent, (ii) the IRS notifies the Paying Agent that the TIN furnished by the payee is incorrect, (iii) the payee fails to certify, under penalties of perjury, that the payee is not subject to backup withholding, or (iv) the IRS notifies the Paying Agent that the payee has failed to report all interest and dividends required to be shown on its federal income tax return. The payment of Merger consideration to selling stockholders constitutes a "reportable payment" for purposes of Section 3406.

(b) Information Reporting — Section 6041 et seq. of the Code. Under Sections 6041, 6042, 6045, and related provisions of the Code, the Paying Agent is required to report the payment of Merger consideration to each selling stockholder on IRS Form 1099-B (Proceeds from Broker and Barter Exchange Transactions) or such other applicable information return as may be required. In order to properly prepare and file these information returns, the Paying Agent must obtain each payee's TIN and other identifying information.

(c) Withholding on Payments to Non-U.S. Persons — Sections 1441 and 1442 of the Code. Under Sections 1441 and 1442 of the Code, a withholding agent (including the Paying Agent) is generally required to deduct and withhold a tax at the statutory rate of 30% (or, if applicable, a reduced rate under an income tax treaty between the United States and the payee's country of residence) from the gross amount of certain payments of fixed or determinable annual or periodical income made to non-U.S. persons. In order to establish eligibility for a reduced rate of withholding under an applicable income tax treaty, a non-U.S. person must deliver a valid IRS Form W-8BEN (for individuals) or IRS Form W-8BEN-E (for entities) to the Paying Agent.

(d) FIRPTA Withholding — Sections 897 and 1445 of the Code. Under Section 1445 of the Code, a transferee of a "United States real property interest" (as defined in Section 897(c) of the Code) is required to deduct and withhold a tax equal to 15% of the amount realized by the transferor on the disposition. To the extent that shares of Company Common Stock could constitute "United States real property interests" (because the Company may be, or may have been at any time during the applicable look-back period, a "United States real property holding corporation" within the meaning of Section 897(c)(2) of the Code), FIRPTA withholding may be relevant to non-U.S. holders. We note that a separate FIRPTA certificate is being delivered by the Company pursuant to Treasury Regulations Section 1.1445-2(c)(3) (certifying that the Company is not, and has not been during the relevant period, a United States real property holding corporation), which, if valid, should generally obviate the need for FIRPTA withholding. Nevertheless, individual W-8 forms are still required from non-U.S. holders to confirm their foreign status and to support any claim of treaty eligibility for the purposes of Sections 1441 and 1442 withholding.

(e) FATCA — Sections 1471 through 1474 of the Code. Under the Foreign Account Tax Compliance Act ("FATCA"), codified in Sections 1471 through 1474 of the Code, withholding at a rate of 30% may be imposed on certain payments made to foreign financial institutions and certain other non-U.S. entities that fail to comply with the FATCA reporting and certification requirements. Non-U.S. persons delivering IRS Form W-8BEN-E are required to certify their FATCA (Chapter 4) status.

The foregoing provisions collectively require the Paying Agent (and, by extension, the Buyer and its counsel) to obtain a properly completed and executed IRS Form W-9 from each U.S. person payee, and a properly completed and executed IRS Form W-8BEN, W-8BEN-E, W-8IMY, or W-8ECI (as applicable) from each non-U.S. person payee, prior to the disbursement of the Merger consideration.

3. Request to Luminex Systems Holdings Inc. (the Company)

We hereby request that the Company deliver the following to Calderwood & Harkness LLP and the Paying Agent:

(a) A properly completed and executed IRS Form W-9 (Request for Taxpayer Identification Number and Certification) for Luminex Systems Holdings Inc., confirming the Company's Employer Identification Number (EIN: 86-2547193). This form is required in connection with the payment of any amounts to or on behalf of the Company at or following the closing of the Merger, including any amounts payable under the working capital adjustment provisions of the Merger Agreement, and for the FIRPTA certificate compliance package being prepared by the Company pursuant to Section 8.14 of the Merger Agreement and Treasury Regulations Section 1.1445-2(c)(3).

(b) A properly completed and executed IRS Form W-9 for Luminex Systems Inc., a wholly owned domestic subsidiary of the Company (EIN: 86-2547210). This form is requested because certain payments in the closing funds flow may be received by or attributed to Luminex Systems Inc. as an operating subsidiary, including intercompany settlement amounts and the repayment of intercompany indebtedness at or prior to the closing.

We request that both forms be signed by an authorized officer of the respective entity and that the information provided thereon be current and accurate as of the date of execution. If any information on a previously submitted Form W-9 has changed (including, without limitation, the entity's legal name, address, or EIN), please provide an updated form reflecting the current information.

4. Request to Selling Stockholders — United States Persons

Each selling stockholder that is a "United States person" (as defined in Section 7701(a)(30) of the Code) must deliver a properly completed and executed IRS Form W-9 (Request for Taxpayer Identification Number and Certification) to Calderwood & Harkness LLP and the Paying Agent. For purposes of this letter, the term "United States person" generally includes (i) a citizen or resident of the United States, (ii) a domestic partnership, (iii) a domestic corporation, (iv) any estate the income of which is subject to United States federal income tax regardless of its source, and (v) certain trusts that are subject to the primary supervision of a court within the United States and with respect to which one or more United States persons have the authority to control all substantial decisions.

Based on the capitalization table provided to us by the Company and the Buyer's records, the following selling stockholders are expected to be United States persons and are hereby requested to deliver a completed IRS Form W-9:

(a) Ridgeline Growth Equity Fund II LP

Ridgeline Growth Equity Fund II LP ("Ridgeline") holds approximately 52% of the outstanding Company Common Stock (approximately 72,800,000 fully diluted shares). At the Per Share Merger Consideration of $20.00 per share, Ridgeline's expected gross proceeds from the Merger are approximately $1,456,000,000. As a Delaware limited partnership, Ridgeline should provide its Employer Identification Number on the Form W-9 and should certify its exempt payee status under the backup withholding rules if applicable (for example, by entering the appropriate exempt payee code on Line 4 of the form if Ridgeline qualifies as an organization exempt from tax under Section 501(a), a corporation, or another exempt payee category listed in the Form W-9 instructions). We note that partnerships are generally not exempt payees for backup withholding purposes unless they fall within one of the enumerated exemption categories; accordingly, Ridgeline should carefully review the instructions to Line 4 and consult with its own tax advisors as to whether it qualifies for an exemption.

(b) Meridian Venture Partners IV LP

Meridian Venture Partners IV LP ("Meridian") holds approximately 20% of the outstanding Company Common Stock (approximately 28,000,000 fully diluted shares). At the Per Share Merger Consideration of $20.00 per share, Meridian's expected gross proceeds from the Merger are approximately $560,000,000. As a Delaware limited partnership, Meridian should likewise provide its Employer Identification Number on the Form W-9 and certify its exempt payee status if applicable, subject to the same considerations noted above with respect to Ridgeline.

Certain members of the Company's management team and other employee stockholders hold, in the aggregate, approximately 28% of the outstanding Company Common Stock (approximately 39,200,000 fully diluted shares). As described in the Merger Agreement and the related rollover agreements, a portion of each management participant's equity will be rolled over into equity of Parent or an affiliate thereof, and the remainder will be converted into the right to receive the Per Share Merger Consideration in cash. The specific management and employee stockholders known to us as of the date hereof, together with their approximate equity holdings, cash-out consideration, and rollover consideration, are as follows:

Each management and employee holder who will receive any portion of the Per Share Merger Consideration in cash is required to individually provide a completed IRS Form W-9, regardless of whether such holder is also participating in the rollover. The obligation to provide Form W-9 is personal to each payee and cannot be satisfied by a form delivered by the Company on such holder's behalf.

Each Form W-9 submitted by a selling stockholder who is a United States person must include the following certifications, made under penalties of perjury:

(1) The TIN shown on the form is the payee's correct taxpayer identification number (or the payee is waiting for a number to be issued);

(2) The payee is not subject to backup withholding because (a) the payee is exempt from backup withholding, (b) the payee has not been notified by the IRS that the payee is subject to backup withholding as a result of a failure to report all interest or dividends, or (c) the IRS has notified the payee that the payee is no longer subject to backup withholding; and

(3) The payee is a United States person (including a United States resident alien).

We note that for any management participant who is a U.S. resident but not a U.S. citizen (i.e., a U.S. resident alien for federal income tax purposes), the IRS Form W-9 remains the appropriate form to deliver, provided that such individual qualifies as a "United States person" under Section 7701(a)(30) of the Code by virtue of meeting the substantial presence test under Section 7701(b) or holding a lawful permanent resident card (i.e., "green card"). If any such individual is uncertain of his or her tax residency status, we strongly encourage that individual to consult with his or her own tax advisor prior to completing the applicable form.

5. Request to Selling Stockholders — Non-United States Persons

Any selling stockholder that is not a "United States person" (as defined in Section 7701(a)(30) of the Code) (a "Non-U.S. Holder") must instead deliver the appropriate IRS Form W-8 series form to Calderwood & Harkness LLP and the Paying Agent. The specific form required depends on the Non-U.S. Holder's status and circumstances, as follows:

(a) IRS Form W-8BEN (Certificate of Foreign Status of Beneficial Owner for United States Tax Withholding and Reporting — Individuals): This form should be completed by any individual selling stockholder who is not a United States person. Form W-8BEN is used to certify the individual's foreign status and, if applicable, to claim a reduced rate of withholding under an income tax treaty between the United States and the individual's country of tax residence. The individual must specify the country of citizenship, the country of tax residence, and (if claiming treaty benefits) the applicable treaty article and the rate of withholding claimed.

(b) IRS Form W-8BEN-E (Certificate of Status of Beneficial Owner for United States Tax Withholding and Reporting — Entities): This form should be completed by any entity selling stockholder that is not a United States person. Form W-8BEN-E is used to certify the entity's foreign status, its classification for Chapter 4 (FATCA) purposes, and, if applicable, to claim a reduced rate of withholding under an income tax treaty. The entity must identify its country of incorporation or organization, its FATCA status (e.g., active NFFE, passive NFFE, participating FFI, etc.), and, if claiming treaty benefits, the applicable treaty country, article, and rate of withholding claimed.

(c) IRS Form W-8IMY (Certificate of Foreign Intermediary, Foreign Flow-Through Entity, or Certain U.S. Branches for United States Tax Withholding and Reporting): This form should be completed by any intermediary or flow-through entity that receives the Merger consideration on behalf of one or more beneficial owners. If Form W-8IMY is required, it must be accompanied by a withholding statement and the appropriate underlying beneficial owner documentation (i.e., Forms W-9, W-8BEN, or W-8BEN-E for each underlying beneficial owner, as applicable).

(d) IRS Form W-8ECI (Certificate of Foreign Person's Claim That Income Is Effectively Connected with the Conduct of a Trade or Business in the United States): This form should be completed by any Non-U.S. Holder that claims the Merger consideration is effectively connected with the conduct of a trade or business within the United States (within the meaning of Section 864 of the Code). Income that is so effectively connected is generally not subject to the 30% withholding tax under Sections 1441–1442, but is instead subject to regular U.S. federal income tax on a net-income basis.

The determination of whether a selling stockholder is a United States person or a Non-U.S. Holder is based on such stockholder's own tax status and is not made by Calderwood & Harkness LLP, the Buyer, or the Paying Agent. Any stockholder who is uncertain of its classification should consult its own tax advisor prior to completing the applicable form.

We also note, for informational purposes, that certain selling stockholders may receive amounts through or attributable to Luminex Systems AG, a Swiss subsidiary of the Company. Under Swiss tax law, withholding tax may be imposed on certain distributions at the Swiss statutory rate of 35%, which may be reduced to 5% under the Convention between the United States of America and the Swiss Confederation for the Avoidance of Double Taxation with Respect to Taxes on Income (the "U.S.-Switzerland Income Tax Treaty") for eligible recipients. However, this letter concerns U.S. federal tax forms only; Swiss tax withholding matters, including any required Swiss tax forms or claims for treaty relief under the U.S.-Switzerland Income Tax Treaty, are being addressed separately and will be the subject of separate correspondence from the Company's Swiss tax advisors and/or Caldwell, Raines & Sheppard LLP.

6. Instructions for Completion and Delivery

6.1 Form W-9 Instructions

For the convenience of each selling stockholder required to complete an IRS Form W-9, we provide the following line-by-line guidance. A blank copy of IRS Form W-9 (Rev. current) is enclosed with this letter.

Line 1 — Name. Enter the legal name of the payee exactly as it appears on the payee's most recently filed U.S. federal income tax return. For individuals, this is typically the first name, middle initial, and last name. For entities, this is the legal entity name as registered with the IRS. Please do not enter nicknames, abbreviations, or informal names.

Line 2 — Business name/disregarded entity name. If the payee has a business name, trade name, doing-business-as ("DBA") name, or disregarded entity name that is different from the name entered on Line 1, enter that name on Line 2. For example, if a single-member LLC that is disregarded as an entity separate from its owner for U.S. federal tax purposes is the payee, the owner's name should appear on Line 1 and the LLC's name should appear on Line 2.

Line 3 — Federal tax classification. Check the appropriate box to indicate the payee's federal tax classification. The available classifications are: Individual/sole proprietor or single-member LLC; C Corporation; S Corporation; Partnership; Trust/estate; Limited liability company (with indication of the applicable tax classification — C, S, or P); or Other. For selling stockholders that are limited partnerships (such as Ridgeline Growth Equity Fund II LP and Meridian Venture Partners IV LP), check the "Partnership" box. For individual management/employee stockholders, check the "Individual/sole proprietor or single-member LLC" box.

Line 4 — Exemptions. If applicable, enter the exempt payee code and/or the exemption from FATCA reporting code. The exempt payee codes are listed in the Form W-9 instructions and include, among others, Code 1 (an organization exempt from tax under Section 501(a), any IRA, or a custodial account under Section 403(b)(7) if the account satisfies the requirements of Section 401(f)(2)), Code 2 (the United States or any of its agencies or instrumentalities), Code 5 (a corporation), and Code 13 (a registered dealer in securities, commodities, or derivative financial instruments). Most individual payees will not qualify for an exemption and should leave Line 4 blank. Partnerships should carefully review the instructions to determine if they qualify as exempt payees.

Lines 5 and 6 — Address. Enter the payee's U.S. address, including street address, city, state, and ZIP code. This address will be used by the Paying Agent for purposes of mailing IRS Form 1099-B and any other applicable information returns. If the payee has a foreign address, enter the foreign address details in the space provided.

Part I — Taxpayer Identification Number. Enter the payee's Social Security Number ("SSN") (for individuals) or Employer Identification Number ("EIN") (for entities). Do NOT leave this field blank. An incomplete Form W-9 — including a form with a missing or illegible TIN — will be rejected, and backup withholding at the rate of 24% will be applied to all Merger consideration payable to such payee until a valid Form W-9 is received.

Part II — Certification. Sign and date the form. By signing, the payee certifies under penalties of perjury that (1) the TIN shown on the form is the payee's correct TIN (or the payee is waiting for a number to be issued), (2) the payee is not subject to backup withholding, (3) the payee is a U.S. citizen or other U.S. person, and (4) the FATCA code(s) entered on the form (if any) are correct. If the payee has been notified by the IRS that the payee is currently subject to backup withholding because of underreporting interest or dividends on the payee's tax return, the payee must cross out item (2) in the certification before signing.

We emphasize that Forms W-9 with blank or incomplete TIN fields, unsigned forms, or forms that are otherwise not properly completed will not be accepted and will result in backup withholding being imposed on the applicable Merger consideration.

6.2 Form W-8 Instructions

Non-U.S. Holders should refer to the IRS instructions accompanying the applicable Form W-8 series form, copies of which are available on the IRS website at www.irs.gov. Blank copies of IRS Form W-8BEN (Rev. current) and IRS Form W-8BEN-E (Rev. current) are enclosed with this letter.

For selling stockholders completing IRS Form W-8BEN-E (entities), we draw particular attention to the following sections, which must be completed fully and accurately:

Part I — Identification of Beneficial Owner. Enter the entity's legal name, country of incorporation or organization, and permanent address. Provide the entity's foreign TIN (if applicable) and, if the entity has been issued a U.S. TIN, the U.S. TIN.

Part II — Disregarded Entity or Branch Receiving Payment. Complete this Part only if the entity identified in Part I is a disregarded entity or if the payment is being received by a branch of the entity.

Part III — Claim of Tax Treaty Benefits. If the entity is claiming a reduced rate of withholding under an income tax treaty between the United States and the entity's country of tax residence, complete Part III. Specify the country under whose treaty the entity is claiming benefits, the applicable treaty article, the rate of withholding claimed, and the type of income. The entity must also certify that it is the beneficial owner of the income and that it meets the limitation on benefits ("LOB") provisions of the applicable treaty, if any.

Part XXV (or applicable Part for Chapter 4 / FATCA Status). Identify the entity's FATCA classification (Chapter 4 status) by checking the appropriate box (e.g., active NFFE, passive NFFE, participating FFI, nonparticipating FFI, owner-documented FFI, etc.) and provide any required additional information, including the entity's GIIN (Global Intermediary Identification Number), if applicable.

For selling stockholders completing IRS Form W-8BEN (individuals), the following sections must be completed:

Part I — Identification of Beneficial Owner. Enter the individual's legal name, country of citizenship, permanent residence address, and mailing address (if different). Provide the individual's foreign TIN (if applicable), date of birth, and, if available, U.S. TIN.

Part II — Claim of Tax Treaty Benefits. If the individual is claiming treaty benefits, identify the country of residence for treaty purposes, the applicable treaty article, the rate of withholding claimed, and the type of income. Certify that the individual is the beneficial owner and meets the conditions of the applicable treaty article.

Part III — Certification. Sign and date the form. The form must be signed by the beneficial owner (or, if the beneficial owner is a minor or otherwise unable to sign, by a legal guardian or authorized representative).

6.3 Delivery Deadline and Method

We respectfully request that all completed forms be delivered no later than five (5) business days prior to the anticipated closing date of the Merger. Based on the current timeline set forth in the Merger Agreement and the status of regulatory approvals, we currently estimate that the closing will occur in July or August 2025. We will provide a more specific deadline as the closing date becomes more certain; however, we encourage all parties to submit their completed forms as promptly as possible to avoid any last-minute delays.

Completed forms should be delivered as follows:

(a) Email (PDF). Scanned PDF copies of executed forms should be emailed to:

Ryan Kowalski, Lead Associate Calderwood & Harkness LLP

Email: ryan.kowalski@calderwoodharkness.com

With a copy to:

Megan Chu, Working Associate Calderwood & Harkness LLP

Email: megan.chu@calderwoodharkness.com

(b) Hard-Copy Originals. Original executed forms should follow promptly by overnight courier (Severin Partners LLC, Halcyon Partners LLC, or equivalent) to:

Calderwood & Harkness LLP 7 Times Square New York, NY 10036

Attn: Ryan Kowalski

Atlas Shareholder Services Inc. 6201 15th Avenue Brooklyn, NY 11219

Attn: Dennis Carmichael

Email: dcarmichael@atlasshareservices.com

We note that the Paying Agent (Atlas Shareholder Services Inc.) will also be distributing Letters of Transmittal to all cashing-out stockholders in connection with the Merger, which Letters of Transmittal will include a request for IRS Form W-9 or the applicable IRS Form W-8, as the case may be. This letter serves as advance notice of the tax form requirements and is intended to facilitate timely collection of the forms prior to the distribution of the Letters of Transmittal. It should not be treated as duplicative of the Letter of Transmittal process. Stockholders who submit their forms in response to this letter will not need to resubmit the same forms with their Letter of Transmittal, provided that the forms remain valid and accurate as of the closing date.

7. Consequences of Non-Compliance

We wish to clearly advise all parties of the consequences of failing to deliver the requested tax certification forms prior to the closing of the Merger:

(a) Backup Withholding on U.S. Persons. If a valid IRS Form W-9 is not received from a U.S. person prior to or at the time of the disbursement of Merger consideration, the Paying Agent will be required by law to deduct and withhold backup withholding tax at the rate of 24% from the gross Merger consideration payable to such holder. This withholding will be applied automatically and without exception. The Paying Agent has no discretion to waive or reduce backup withholding in the absence of a valid Form W-9.

(b) Withholding on Non-U.S. Persons. If a valid IRS Form W-8BEN, W-8BEN-E, or other applicable Form W-8 is not received from a Non-U.S. Holder prior to or at the time of the disbursement of Merger consideration, the Paying Agent will be required by law to deduct and withhold tax at the statutory rate of 30% from the gross Merger consideration payable to such holder under Sections 1441 and 1442 of the Code. If a valid Form W-8 is received but claims a reduced rate of withholding under an applicable income tax treaty, withholding will be imposed at the applicable treaty rate (which may be lower than 30%, depending on the terms of the treaty and the type of income). In the absence of a valid treaty claim, the full 30% statutory rate will apply.

(c) Credit or Refund of Withheld Amounts. Amounts withheld as backup withholding or under Sections 1441–1442 of the Code are not additional taxes but are generally creditable against the holder's U.S. federal income tax liability. A holder from whom tax has been withheld may claim a credit for the amount withheld on its U.S. federal income tax return for the applicable taxable year or, if the amount withheld exceeds the holder's U.S. federal income tax liability, may claim a refund of the excess by filing an appropriate tax return with the IRS. However, the process of obtaining a credit or refund may involve significant delay — in some cases, a year or more — and may require the holder to file a U.S. federal income tax return that the holder would not otherwise be required to file. Accordingly, we strongly encourage all selling stockholders to provide the requested forms promptly and in complete form to avoid the imposition of withholding and the associated inconvenience and delay.

8. Request for Coordination by the Company

We respectfully request that Annelise Gruber, in her capacity as Chief Financial Officer of Luminex Systems Holdings Inc., coordinate with the Company's management team and employee stockholders to ensure the timely collection and delivery of IRS Forms W-9 (or the applicable IRS Form W-8, as the case may be) from all holders of Company Common Stock who will receive Merger consideration at the closing.

As noted above, the Company's management and employee stockholders hold, in the aggregate, approximately 28% of the outstanding Company Common Stock (approximately 39,200,000 fully diluted shares), representing a significant portion of the Company's capitalization. Given the large number of individual holders — including participants in the Company's equity incentive plans (including, without limitation, holders of stock options, restricted stock units, and restricted stock awards that will be accelerated, vested, or cashed out in connection with the Merger) — it is critical that the Company take proactive steps to communicate the Form W-9/W-8 requirement to all such holders and to assist in the collection and delivery of the completed forms.

In addition, we request that the Company provide Calderwood & Harkness LLP with a complete and current list of all registered holders of Company Common Stock (including holders of vested and unvested equity awards that will be converted into the right to receive Merger consideration), together with the following information for each holder:

(a) Full legal name of the holder;

(b) Mailing address of the holder;

(c) Number of shares of Company Common Stock held (and, separately, the number of shares subject to stock options, RSUs, or other equity awards);

(d) To the extent known by the Company, an indication of whether the holder is a United States person or a Non-U.S. Holder for U.S. federal income tax purposes; and

(e) Such other information as may be reasonably necessary to facilitate the Paying Agent's distribution of the Letter of Transmittal and tax form collection.

This stockholder list should be provided to Calderwood & Harkness LLP at the earliest practicable date and in any event no later than fifteen (15) business days prior to the anticipated closing date.

9. Contact Information

For questions regarding this letter, the required tax certification forms, or the delivery process, please contact the following individuals at Calderwood & Harkness LLP:

Ryan Kowalski, Lead Associate (Mergers & Acquisitions) Telephone: (212) 558-4137

Email: ryan.kowalski@calderwoodharkness.com

Megan Chu, Working Associate (Mergers & Acquisitions) Telephone: (212) 558-4592

Email: megan.chu@calderwoodharkness.com

For tax-specific questions:

Sylvia Hartwell, Partner (Tax) Telephone: (212) 558-3021

Email: sylvia.hartwell@calderwoodharkness.com

We also note that the Buyer's independent accounting and tax advisor, Pendleton & Associates LLP (Richard Chow, Engagement Partner, 30 Rockefeller Plaza, Suite 2600, New York, NY 10112; telephone: (212) 489-7700; email: rchow@pendletonassociates.com), is available for consultation on matters relating to the purchase-price allocation, the potential Section 338(h)(10) election, and related transaction-level tax matters. However, each selling stockholder is strongly encouraged to consult its own independent tax advisor regarding the personal income tax consequences of the Merger, including the determination of gain or loss on the exchange of Company Common Stock for the Merger consideration, the availability of any applicable exemptions or treaty benefits, and the applicable state, local, and non-U.S. tax consequences of the transaction. Neither Calderwood & Harkness LLP, the Buyer, the Paying Agent, nor Pendleton & Associates LLP is providing tax advice to any selling stockholder, and nothing in this letter should be construed as tax advice to any party other than the Buyer.

10. Confidentiality Notice

This letter and the IRS Forms W-9, W-8BEN, W-8BEN-E, and other tax certification forms collected in response hereto contain sensitive taxpayer information that is protected under federal law, including Section 6103 of the Internal Revenue Code, which imposes strict confidentiality obligations with respect to tax return information and taxpayer identity information. The information collected in response to this letter will be used solely for the purposes of complying with the tax reporting and withholding obligations of the Paying Agent, the Buyer, and their authorized agents in connection with the Merger, and for no other purpose.

The information will be shared only with the following parties, to the extent necessary for the purposes described above:

(a) Atlas Shareholder Services Inc. (the Paying Agent);

(b) Ardent Apex Holdings Inc. (Parent) and its authorized representatives;

(d) Calderwood & Harkness LLP (counsel to the Buyer);

(e) Pendleton & Associates LLP (tax advisor to the Buyer); and

(f) Such other agents or advisors as may be necessary to comply with applicable tax reporting and withholding obligations, subject to appropriate confidentiality protections.

No taxpayer information collected in response to this letter will be disclosed to any other party except as required by law or regulation or with the prior written consent of the applicable taxpayer.

We thank you in advance for your prompt cooperation and attention to this matter. The timely collection of the requested tax certification forms is a critical step in ensuring a smooth and efficient closing of the Merger and the prompt disbursement of the Merger consideration to all selling stockholders. Please do not hesitate to contact us with any questions.

Very truly yours,

CALDERWOOD & HARKNESS LLP

By: ________

Ryan Kowalski Associate 7 Times Square New York, NY 10036 Telephone: (212) 558-4137

Email: ryan.kowalski@calderwoodharkness.com

Enclosures:

1. IRS Form W-9 (Request for Taxpayer Identification Number and Certification) (Rev. current) — Blank

2. IRS Form W-8BEN (Certificate of Foreign Status of Beneficial Owner for United States Tax Withholding and Reporting — Individuals) (Rev. current) — Blank

3. IRS Form W-8BEN-E (Certificate of Status of Beneficial Owner for United States Tax Withholding and Reporting — Entities) (Rev. current) — Blank

4. Summary Instruction Sheet (prepared by Calderwood & Harkness LLP) — Identifying which form each category of selling stockholder should complete

cc: (via email)

James Prentice, Partner, Calderwood & Harkness LLP Sandra Tung, Partner, Calderwood & Harkness LLP Sylvia Hartwell, Partner, Calderwood & Harkness LLP Theodore "Ted" Hargrove, Ardent Capital Partners III LP, 399 Park Avenue, 42nd Floor, New York, NY 10022 Victoria Langford, Ardent Capital Partners III LP, 399 Park Avenue, 42nd Floor, New York, NY 10022 David Ng, CFO, Ardent Capital Partners III LP, 399 Park Avenue, 42nd Floor, New York, NY 10022 Richard Chow, Pendleton & Associates LLP, 30 Rockefeller Plaza, Suite 2600, New York, NY 10112 Patricia Okonkwo, Caldwell, Raines & Sheppard LLP, 51 West 52nd Street, New York, NY 10019 Daniel Feinberg, Caldwell, Raines & Sheppard LLP, 51 West 52nd Street, New York, NY 10019 Dennis Carmichael, Atlas Shareholder Services Inc., 6201 15th Avenue, Brooklyn, NY 11219 Laura Svensson, Continental Fiduciary Trust Company, 60 Wall Street, 24th Floor, New York, NY 10005 (for escrow-related coordination)

Stockholder	Title	Approx. % of Equity	Total Equity Value	Cash-Out Portion	Rollover Portion
Dr. Stefan Kessler	Chief Executive Officer	8.5%	$238,000,000	$95,200,000 (40%)	$142,800,000 (60%)
Annelise Gruber	Chief Financial Officer	4.2%	$117,600,000	$58,800,000 (50%)	$58,800,000 (50%)
Dr. Markus Vogt	Chief Technology Officer	3.8%	$106,400,000	$47,880,000 (45%)	$58,520,000 (55%)
Other management and employee holders	Various	11.5% (aggregate)	$322,000,000 (aggregate)	~$177,100,000 (aggregate)	~$144,900,000 (aggregate)

CONFIDENTIAL
CALDERWOOD & HARKNESS LLP 7 Times Square New York, NY 10036 Tel: (212) 558-4000
Fax: (212) 558-3588
www.calderwoodharkness.com
[__], 2025
VIA EMAIL AND OVERNIGHT COURIER
Luminex Systems Holdings Inc. 2100 Reston Gateway Drive, Suite 800 Reston, VA 20191
Attn: Annelise Gruber, Chief Financial Officer
With copies to:
Ridgeline Growth Equity Fund II LP 200 Clarendon Street, 52nd Floor Boston, MA 02116
Attn: Jonathan Ashford, Managing Partner
Meridian Venture Partners IV LP 600 Montgomery Street, Suite 2800 San Francisco, CA 94111
Attn: Claire Fujimoto, Managing Partner
Caldwell, Raines & Sheppard LLP 51 West 52nd Street New York, NY 10019
Attn: Patricia Okonkwo / Daniel Feinberg
Atlas Shareholder Services Inc. 6201 15th Avenue Brooklyn, NY 11219
Attn: Dennis Carmichael
Re: Acquisition of Luminex Systems Holdings Inc. — Request for IRS Form W-9 / W-8BEN / W-8BEN-E Agreement and Plan of Merger, dated as of March 24, 2025, by and among Ardent Apex Holdings Inc., Ardent Apex Merger Sub Inc., and Luminex Systems Holdings Inc. Calderwood & Harkness LLP Matter No. 1001-00004
Dear Ms. Gruber and Selling Stockholders:
1. Introduction and Purpose
Calderwood & Harkness LLP serves as legal counsel to Ardent Capital Partners III LP (the "Buyer" or "Sponsor") in connection with the pending acquisition of Luminex Systems Holdings Inc. (the "Company" or the "Target") pursuant to the Agreement and Plan of Merger, dated as of March 24, 2025 (as the same may be amended, supplemented, or otherwise modified from time to time, the "Merger Agreement"), by and among Ardent Apex Holdings Inc., a Delaware corporation ("Parent"), Ardent Apex Merger Sub Inc., a Delaware corporation and wholly owned subsidiary of Parent ("Merger Sub"), and the Company.
As you are aware, the Merger Agreement provides for a reverse triangular merger pursuant to which Merger Sub will merge with and into the Company (the "Merger"), with the Company surviving the Merger as a wholly owned subsidiary of Parent (the "Surviving Corporation"). At the effective time of the Merger (the "Effective Time"), each share of common stock, par value $0.001 per share, of the Company ("Company Common Stock") issued and outstanding immediately prior to the Effective Time (other than shares held by Parent, Merger Sub, or the Company (as treasury shares), and other than dissenting shares and management rollover shares) will be converted into the right to receive $20.00 per share in cash, without interest (the "Per Share Merger Consideration"). On a fully diluted basis, the aggregate Merger consideration (the "Aggregate Merger Consideration") is approximately $2,800,000,000 (two billion eight hundred million dollars), representing $20.00 per share across 140,000,000 fully diluted shares of Company Common Stock, payable in cash (except for management rollover equity, which is subject to separate rollover agreements).
The purpose of this letter is to request that the Company and each selling stockholder of the Company provide completed Internal Revenue Service ("IRS") tax certification forms in advance of the anticipated closing of the Merger. In connection with the payment of the Merger consideration at closing, United States federal tax law requires the Buyer (through the paying agent, Atlas Shareholder Services Inc. (the "Paying Agent")) to collect taxpayer identification information from each payee in order to comply with the information reporting and backup withholding obligations imposed by the Internal Revenue Code of 1986, as amended (the "Code"), and the regulations promulgated thereunder (the "Treasury Regulations"). This letter describes the specific forms required, the legal basis for the request, and the consequences of failing to provide the requested certifications.
We respectfully request your prompt attention to this matter, as the timely collection of the forms described herein is essential to ensuring that the closing of the Merger proceeds on schedule and that the payment of the Merger consideration to the selling stockholders is not subject to unnecessary withholding or delay.
2. Legal Basis for This Request
The request set forth in this letter is made pursuant to, and in furtherance of compliance with, the following provisions of federal tax law:
(a) Backup Withholding — Section 3406 of the Code. Under Section 3406 of the Code, the Paying Agent is required to deduct and withhold a tax (commonly referred to as "backup withholding") at the then-applicable statutory rate (currently 24%) from certain "reportable payments" made to a payee if (i) the payee fails to furnish its correct taxpayer identification number ("TIN") to the Paying Agent, (ii) the IRS notifies the Paying Agent that the TIN furnished by the payee is incorrect, (iii) the payee fails to certify, under penalties of perjury, that the payee is not subject to backup withholding, or (iv) the IRS notifies the Paying Agent that the payee has failed to report all interest and dividends required to be shown on its federal income tax return. The payment of Merger consideration to selling stockholders constitutes a "reportable payment" for purposes of Section 3406.
(b) Information Reporting — Section 6041 et seq. of the Code. Under Sections 6041, 6042, 6045, and related provisions of the Code, the Paying Agent is required to report the payment of Merger consideration to each selling stockholder on IRS Form 1099-B (Proceeds from Broker and Barter Exchange Transactions) or such other applicable information return as may be required. In order to properly prepare and file these information returns, the Paying Agent must obtain each payee's TIN and other identifying information.
(c) Withholding on Payments to Non-U.S. Persons — Sections 1441 and 1442 of the Code. Under Sections 1441 and 1442 of the Code, a withholding agent (including the Paying Agent) is generally required to deduct and withhold a tax at the statutory rate of 30% (or, if applicable, a reduced rate under an income tax treaty between the United States and the payee's country of residence) from the gross amount of certain payments of fixed or determinable annual or periodical income made to non-U.S. persons. In order to establish eligibility for a reduced rate of withholding under an applicable income tax treaty, a non-U.S. person must deliver a valid IRS Form W-8BEN (for individuals) or IRS Form W-8BEN-E (for entities) to the Paying Agent.
(d) FIRPTA Withholding — Sections 897 and 1445 of the Code. Under Section 1445 of the Code, a transferee of a "United States real property interest" (as defined in Section 897(c) of the Code) is required to deduct and withhold a tax equal to 15% of the amount realized by the transferor on the disposition. To the extent that shares of Company Common Stock could constitute "United States real property interests" (because the Company may be, or may have been at any time during the applicable look-back period, a "United States real property holding corporation" within the meaning of Section 897(c)(2) of the Code), FIRPTA withholding may be relevant to non-U.S. holders. We note that a separate FIRPTA certificate is being delivered by the Company pursuant to Treasury Regulations Section 1.1445-2(c)(3) (certifying that the Company is not, and has not been during the relevant period, a United States real property holding corporation), which, if valid, should generally obviate the need for FIRPTA withholding. Nevertheless, individual W-8 forms are still required from non-U.S. holders to confirm their foreign status and to support any claim of treaty eligibility for the purposes of Sections 1441 and 1442 withholding.
(e) FATCA — Sections 1471 through 1474 of the Code. Under the Foreign Account Tax Compliance Act ("FATCA"), codified in Sections 1471 through 1474 of the Code, withholding at a rate of 30% may be imposed on certain payments made to foreign financial institutions and certain other non-U.S. entities that fail to comply with the FATCA reporting and certification requirements. Non-U.S. persons delivering IRS Form W-8BEN-E are required to certify their FATCA (Chapter 4) status.
The foregoing provisions collectively require the Paying Agent (and, by extension, the Buyer and its counsel) to obtain a properly completed and executed IRS Form W-9 from each U.S. person payee, and a properly completed and executed IRS Form W-8BEN, W-8BEN-E, W-8IMY, or W-8ECI (as applicable) from each non-U.S. person payee, prior to the disbursement of the Merger consideration.
3. Request to Luminex Systems Holdings Inc. (the Company)
We hereby request that the Company deliver the following to Calderwood & Harkness LLP and the Paying Agent:
(a) A properly completed and executed IRS Form W-9 (Request for Taxpayer Identification Number and Certification) for Luminex Systems Holdings Inc., confirming the Company's Employer Identification Number (EIN: 86-2547193). This form is required in connection with the payment of any amounts to or on behalf of the Company at or following the closing of the Merger, including any amounts payable under the working capital adjustment provisions of the Merger Agreement, and for the FIRPTA certificate compliance package being prepared by the Company pursuant to Section 8.14 of the Merger Agreement and Treasury Regulations Section 1.1445-2(c)(3).
(b) A properly completed and executed IRS Form W-9 for Luminex Systems Inc., a wholly owned domestic subsidiary of the Company (EIN: 86-2547210). This form is requested because certain payments in the closing funds flow may be received by or attributed to Luminex Systems Inc. as an operating subsidiary, including intercompany settlement amounts and the repayment of intercompany indebtedness at or prior to the closing.
We request that both forms be signed by an authorized officer of the respective entity and that the information provided thereon be current and accurate as of the date of execution. If any information on a previously submitted Form W-9 has changed (including, without limitation, the entity's legal name, address, or EIN), please provide an updated form reflecting the current information.
4. Request to Selling Stockholders — United States Persons
Each selling stockholder that is a "United States person" (as defined in Section 7701(a)(30) of the Code) must deliver a properly completed and executed IRS Form W-9 (Request for Taxpayer Identification Number and Certification) to Calderwood & Harkness LLP and the Paying Agent. For purposes of this letter, the term "United States person" generally includes (i) a citizen or resident of the United States, (ii) a domestic partnership, (iii) a domestic corporation, (iv) any estate the income of which is subject to United States federal income tax regardless of its source, and (v) certain trusts that are subject to the primary supervision of a court within the United States and with respect to which one or more United States persons have the authority to control all substantial decisions.
Based on the capitalization table provided to us by the Company and the Buyer's records, the following selling stockholders are expected to be United States persons and are hereby requested to deliver a completed IRS Form W-9:
(a) Ridgeline Growth Equity Fund II LP
Ridgeline Growth Equity Fund II LP ("Ridgeline") holds approximately 52% of the outstanding Company Common Stock (approximately 72,800,000 fully diluted shares). At the Per Share Merger Consideration of $20.00 per share, Ridgeline's expected gross proceeds from the Merger are approximately $1,456,000,000. As a Delaware limited partnership, Ridgeline should provide its Employer Identification Number on the Form W-9 and should certify its exempt payee status under the backup withholding rules if applicable (for example, by entering the appropriate exempt payee code on Line 4 of the form if Ridgeline qualifies as an organization exempt from tax under Section 501(a), a corporation, or another exempt payee category listed in the Form W-9 instructions). We note that partnerships are generally not exempt payees for backup withholding purposes unless they fall within one of the enumerated exemption categories; accordingly, Ridgeline should carefully review the instructions to Line 4 and consult with its own tax advisors as to whether it qualifies for an exemption.
(b) Meridian Venture Partners IV LP
Meridian Venture Partners IV LP ("Meridian") holds approximately 20% of the outstanding Company Common Stock (approximately 28,000,000 fully diluted shares). At the Per Share Merger Consideration of $20.00 per share, Meridian's expected gross proceeds from the Merger are approximately $560,000,000. As a Delaware limited partnership, Meridian should likewise provide its Employer Identification Number on the Form W-9 and certify its exempt payee status if applicable, subject to the same considerations noted above with respect to Ridgeline.
(c) Management Rollover Participants and Employee Stockholders
Certain members of the Company's management team and other employee stockholders hold, in the aggregate, approximately 28% of the outstanding Company Common Stock (approximately 39,200,000 fully diluted shares). As described in the Merger Agreement and the related rollover agreements, a portion of each management participant's equity will be rolled over into equity of Parent or an affiliate thereof, and the remainder will be converted into the right to receive the Per Share Merger Consideration in cash. The specific management and employee stockholders known to us as of the date hereof, together with their approximate equity holdings, cash-out consideration, and rollover consideration, are as follows:
Each management and employee holder who will receive any portion of the Per Share Merger Consideration in cash is required to individually provide a completed IRS Form W-9, regardless of whether such holder is also participating in the rollover. The obligation to provide Form W-9 is personal to each payee and cannot be satisfied by a form delivered by the Company on such holder's behalf.
Each Form W-9 submitted by a selling stockholder who is a United States person must include the following certifications, made under penalties of perjury:
(1) The TIN shown on the form is the payee's correct taxpayer identification number (or the payee is waiting for a number to be issued);
(2) The payee is not subject to backup withholding because (a) the payee is exempt from backup withholding, (b) the payee has not been notified by the IRS that the payee is subject to backup withholding as a result of a failure to report all interest or dividends, or (c) the IRS has notified the payee that the payee is no longer subject to backup withholding; and
(3) The payee is a United States person (including a United States resident alien).
We note that for any management participant who is a U.S. resident but not a U.S. citizen (i.e., a U.S. resident alien for federal income tax purposes), the IRS Form W-9 remains the appropriate form to deliver, provided that such individual qualifies as a "United States person" under Section 7701(a)(30) of the Code by virtue of meeting the substantial presence test under Section 7701(b) or holding a lawful permanent resident card (i.e., "green card"). If any such individual is uncertain of his or her tax residency status, we strongly encourage that individual to consult with his or her own tax advisor prior to completing the applicable form.
5. Request to Selling Stockholders — Non-United States Persons
Any selling stockholder that is not a "United States person" (as defined in Section 7701(a)(30) of the Code) (a "Non-U.S. Holder") must instead deliver the appropriate IRS Form W-8 series form to Calderwood & Harkness LLP and the Paying Agent. The specific form required depends on the Non-U.S. Holder's status and circumstances, as follows:
(a) IRS Form W-8BEN (Certificate of Foreign Status of Beneficial Owner for United States Tax Withholding and Reporting — Individuals): This form should be completed by any individual selling stockholder who is not a United States person. Form W-8BEN is used to certify the individual's foreign status and, if applicable, to claim a reduced rate of withholding under an income tax treaty between the United States and the individual's country of tax residence. The individual must specify the country of citizenship, the country of tax residence, and (if claiming treaty benefits) the applicable treaty article and the rate of withholding claimed.
(b) IRS Form W-8BEN-E (Certificate of Status of Beneficial Owner for United States Tax Withholding and Reporting — Entities): This form should be completed by any entity selling stockholder that is not a United States person. Form W-8BEN-E is used to certify the entity's foreign status, its classification for Chapter 4 (FATCA) purposes, and, if applicable, to claim a reduced rate of withholding under an income tax treaty. The entity must identify its country of incorporation or organization, its FATCA status (e.g., active NFFE, passive NFFE, participating FFI, etc.), and, if claiming treaty benefits, the applicable treaty country, article, and rate of withholding claimed.
(c) IRS Form W-8IMY (Certificate of Foreign Intermediary, Foreign Flow-Through Entity, or Certain U.S. Branches for United States Tax Withholding and Reporting): This form should be completed by any intermediary or flow-through entity that receives the Merger consideration on behalf of one or more beneficial owners. If Form W-8IMY is required, it must be accompanied by a withholding statement and the appropriate underlying beneficial owner documentation (i.e., Forms W-9, W-8BEN, or W-8BEN-E for each underlying beneficial owner, as applicable).
(d) IRS Form W-8ECI (Certificate of Foreign Person's Claim That Income Is Effectively Connected with the Conduct of a Trade or Business in the United States): This form should be completed by any Non-U.S. Holder that claims the Merger consideration is effectively connected with the conduct of a trade or business within the United States (within the meaning of Section 864 of the Code). Income that is so effectively connected is generally not subject to the 30% withholding tax under Sections 1441–1442, but is instead subject to regular U.S. federal income tax on a net-income basis.
The determination of whether a selling stockholder is a United States person or a Non-U.S. Holder is based on such stockholder's own tax status and is not made by Calderwood & Harkness LLP, the Buyer, or the Paying Agent. Any stockholder who is uncertain of its classification should consult its own tax advisor prior to completing the applicable form.
We also note, for informational purposes, that certain selling stockholders may receive amounts through or attributable to Luminex Systems AG, a Swiss subsidiary of the Company. Under Swiss tax law, withholding tax may be imposed on certain distributions at the Swiss statutory rate of 35%, which may be reduced to 5% under the Convention between the United States of America and the Swiss Confederation for the Avoidance of Double Taxation with Respect to Taxes on Income (the "U.S.-Switzerland Income Tax Treaty") for eligible recipients. However, this letter concerns U.S. federal tax forms only; Swiss tax withholding matters, including any required Swiss tax forms or claims for treaty relief under the U.S.-Switzerland Income Tax Treaty, are being addressed separately and will be the subject of separate correspondence from the Company's Swiss tax advisors and/or Caldwell, Raines & Sheppard LLP.
6. Instructions for Completion and Delivery
6.1 Form W-9 Instructions
For the convenience of each selling stockholder required to complete an IRS Form W-9, we provide the following line-by-line guidance. A blank copy of IRS Form W-9 (Rev. current) is enclosed with this letter.
Line 1 — Name. Enter the legal name of the payee exactly as it appears on the payee's most recently filed U.S. federal income tax return. For individuals, this is typically the first name, middle initial, and last name. For entities, this is the legal entity name as registered with the IRS. Please do not enter nicknames, abbreviations, or informal names.
Line 2 — Business name/disregarded entity name. If the payee has a business name, trade name, doing-business-as ("DBA") name, or disregarded entity name that is different from the name entered on Line 1, enter that name on Line 2. For example, if a single-member LLC that is disregarded as an entity separate from its owner for U.S. federal tax purposes is the payee, the owner's name should appear on Line 1 and the LLC's name should appear on Line 2.
Line 3 — Federal tax classification. Check the appropriate box to indicate the payee's federal tax classification. The available classifications are: Individual/sole proprietor or single-member LLC; C Corporation; S Corporation; Partnership; Trust/estate; Limited liability company (with indication of the applicable tax classification — C, S, or P); or Other. For selling stockholders that are limited partnerships (such as Ridgeline Growth Equity Fund II LP and Meridian Venture Partners IV LP), check the "Partnership" box. For individual management/employee stockholders, check the "Individual/sole proprietor or single-member LLC" box.
Line 4 — Exemptions. If applicable, enter the exempt payee code and/or the exemption from FATCA reporting code. The exempt payee codes are listed in the Form W-9 instructions and include, among others, Code 1 (an organization exempt from tax under Section 501(a), any IRA, or a custodial account under Section 403(b)(7) if the account satisfies the requirements of Section 401(f)(2)), Code 2 (the United States or any of its agencies or instrumentalities), Code 5 (a corporation), and Code 13 (a registered dealer in securities, commodities, or derivative financial instruments). Most individual payees will not qualify for an exemption and should leave Line 4 blank. Partnerships should carefully review the instructions to determine if they qualify as exempt payees.
Lines 5 and 6 — Address. Enter the payee's U.S. address, including street address, city, state, and ZIP code. This address will be used by the Paying Agent for purposes of mailing IRS Form 1099-B and any other applicable information returns. If the payee has a foreign address, enter the foreign address details in the space provided.
Part I — Taxpayer Identification Number. Enter the payee's Social Security Number ("SSN") (for individuals) or Employer Identification Number ("EIN") (for entities). Do NOT leave this field blank. An incomplete Form W-9 — including a form with a missing or illegible TIN — will be rejected, and backup withholding at the rate of 24% will be applied to all Merger consideration payable to such payee until a valid Form W-9 is received.
Part II — Certification. Sign and date the form. By signing, the payee certifies under penalties of perjury that (1) the TIN shown on the form is the payee's correct TIN (or the payee is waiting for a number to be issued), (2) the payee is not subject to backup withholding, (3) the payee is a U.S. citizen or other U.S. person, and (4) the FATCA code(s) entered on the form (if any) are correct. If the payee has been notified by the IRS that the payee is currently subject to backup withholding because of underreporting interest or dividends on the payee's tax return, the payee must cross out item (2) in the certification before signing.
We emphasize that Forms W-9 with blank or incomplete TIN fields, unsigned forms, or forms that are otherwise not properly completed will not be accepted and will result in backup withholding being imposed on the applicable Merger consideration.
6.2 Form W-8 Instructions
Non-U.S. Holders should refer to the IRS instructions accompanying the applicable Form W-8 series form, copies of which are available on the IRS website at www.irs.gov. Blank copies of IRS Form W-8BEN (Rev. current) and IRS Form W-8BEN-E (Rev. current) are enclosed with this letter.
For selling stockholders completing IRS Form W-8BEN-E (entities), we draw particular attention to the following sections, which must be completed fully and accurately:
Part I — Identification of Beneficial Owner. Enter the entity's legal name, country of incorporation or organization, and permanent address. Provide the entity's foreign TIN (if applicable) and, if the entity has been issued a U.S. TIN, the U.S. TIN.
Part II — Disregarded Entity or Branch Receiving Payment. Complete this Part only if the entity identified in Part I is a disregarded entity or if the payment is being received by a branch of the entity.
Part III — Claim of Tax Treaty Benefits. If the entity is claiming a reduced rate of withholding under an income tax treaty between the United States and the entity's country of tax residence, complete Part III. Specify the country under whose treaty the entity is claiming benefits, the applicable treaty article, the rate of withholding claimed, and the type of income. The entity must also certify that it is the beneficial owner of the income and that it meets the limitation on benefits ("LOB") provisions of the applicable treaty, if any.
Part XXV (or applicable Part for Chapter 4 / FATCA Status). Identify the entity's FATCA classification (Chapter 4 status) by checking the appropriate box (e.g., active NFFE, passive NFFE, participating FFI, nonparticipating FFI, owner-documented FFI, etc.) and provide any required additional information, including the entity's GIIN (Global Intermediary Identification Number), if applicable.
For selling stockholders completing IRS Form W-8BEN (individuals), the following sections must be completed:
Part I — Identification of Beneficial Owner. Enter the individual's legal name, country of citizenship, permanent residence address, and mailing address (if different). Provide the individual's foreign TIN (if applicable), date of birth, and, if available, U.S. TIN.
Part II — Claim of Tax Treaty Benefits. If the individual is claiming treaty benefits, identify the country of residence for treaty purposes, the applicable treaty article, the rate of withholding claimed, and the type of income. Certify that the individual is the beneficial owner and meets the conditions of the applicable treaty article.
Part III — Certification. Sign and date the form. The form must be signed by the beneficial owner (or, if the beneficial owner is a minor or otherwise unable to sign, by a legal guardian or authorized representative).
6.3 Delivery Deadline and Method
We respectfully request that all completed forms be delivered no later than five (5) business days prior to the anticipated closing date of the Merger. Based on the current timeline set forth in the Merger Agreement and the status of regulatory approvals, we currently estimate that the closing will occur in July or August 2025. We will provide a more specific deadline as the closing date becomes more certain; however, we encourage all parties to submit their completed forms as promptly as possible to avoid any last-minute delays.
Completed forms should be delivered as follows:
(a) Email (PDF). Scanned PDF copies of executed forms should be emailed to:
Ryan Kowalski, Lead Associate Calderwood & Harkness LLP
Email: ryan.kowalski@calderwoodharkness.com
With a copy to:
Megan Chu, Working Associate Calderwood & Harkness LLP
Email: megan.chu@calderwoodharkness.com
(b) Hard-Copy Originals. Original executed forms should follow promptly by overnight courier (Severin Partners LLC, Halcyon Partners LLC, or equivalent) to:
Calderwood & Harkness LLP 7 Times Square New York, NY 10036
Attn: Ryan Kowalski
(c) Copy to Paying Agent. Please also deliver a copy (email or hard copy) to:
Atlas Shareholder Services Inc. 6201 15th Avenue Brooklyn, NY 11219
Attn: Dennis Carmichael
Email: dcarmichael@atlasshareservices.com
We note that the Paying Agent (Atlas Shareholder Services Inc.) will also be distributing Letters of Transmittal to all cashing-out stockholders in connection with the Merger, which Letters of Transmittal will include a request for IRS Form W-9 or the applicable IRS Form W-8, as the case may be. This letter serves as advance notice of the tax form requirements and is intended to facilitate timely collection of the forms prior to the distribution of the Letters of Transmittal. It should not be treated as duplicative of the Letter of Transmittal process. Stockholders who submit their forms in response to this letter will not need to resubmit the same forms with their Letter of Transmittal, provided that the forms remain valid and accurate as of the closing date.
7. Consequences of Non-Compliance
We wish to clearly advise all parties of the consequences of failing to deliver the requested tax certification forms prior to the closing of the Merger:
(a) Backup Withholding on U.S. Persons. If a valid IRS Form W-9 is not received from a U.S. person prior to or at the time of the disbursement of Merger consideration, the Paying Agent will be required by law to deduct and withhold backup withholding tax at the rate of 24% from the gross Merger consideration payable to such holder. This withholding will be applied automatically and without exception. The Paying Agent has no discretion to waive or reduce backup withholding in the absence of a valid Form W-9.
(b) Withholding on Non-U.S. Persons. If a valid IRS Form W-8BEN, W-8BEN-E, or other applicable Form W-8 is not received from a Non-U.S. Holder prior to or at the time of the disbursement of Merger consideration, the Paying Agent will be required by law to deduct and withhold tax at the statutory rate of 30% from the gross Merger consideration payable to such holder under Sections 1441 and 1442 of the Code. If a valid Form W-8 is received but claims a reduced rate of withholding under an applicable income tax treaty, withholding will be imposed at the applicable treaty rate (which may be lower than 30%, depending on the terms of the treaty and the type of income). In the absence of a valid treaty claim, the full 30% statutory rate will apply.
(c) Credit or Refund of Withheld Amounts. Amounts withheld as backup withholding or under Sections 1441–1442 of the Code are not additional taxes but are generally creditable against the holder's U.S. federal income tax liability. A holder from whom tax has been withheld may claim a credit for the amount withheld on its U.S. federal income tax return for the applicable taxable year or, if the amount withheld exceeds the holder's U.S. federal income tax liability, may claim a refund of the excess by filing an appropriate tax return with the IRS. However, the process of obtaining a credit or refund may involve significant delay — in some cases, a year or more — and may require the holder to file a U.S. federal income tax return that the holder would not otherwise be required to file. Accordingly, we strongly encourage all selling stockholders to provide the requested forms promptly and in complete form to avoid the imposition of withholding and the associated inconvenience and delay.
8. Request for Coordination by the Company
We respectfully request that Annelise Gruber, in her capacity as Chief Financial Officer of Luminex Systems Holdings Inc., coordinate with the Company's management team and employee stockholders to ensure the timely collection and delivery of IRS Forms W-9 (or the applicable IRS Form W-8, as the case may be) from all holders of Company Common Stock who will receive Merger consideration at the closing.
As noted above, the Company's management and employee stockholders hold, in the aggregate, approximately 28% of the outstanding Company Common Stock (approximately 39,200,000 fully diluted shares), representing a significant portion of the Company's capitalization. Given the large number of individual holders — including participants in the Company's equity incentive plans (including, without limitation, holders of stock options, restricted stock units, and restricted stock awards that will be accelerated, vested, or cashed out in connection with the Merger) — it is critical that the Company take proactive steps to communicate the Form W-9/W-8 requirement to all such holders and to assist in the collection and delivery of the completed forms.
In addition, we request that the Company provide Calderwood & Harkness LLP with a complete and current list of all registered holders of Company Common Stock (including holders of vested and unvested equity awards that will be converted into the right to receive Merger consideration), together with the following information for each holder:
(a) Full legal name of the holder;
(b) Mailing address of the holder;
(c) Number of shares of Company Common Stock held (and, separately, the number of shares subject to stock options, RSUs, or other equity awards);
(d) To the extent known by the Company, an indication of whether the holder is a United States person or a Non-U.S. Holder for U.S. federal income tax purposes; and
(e) Such other information as may be reasonably necessary to facilitate the Paying Agent's distribution of the Letter of Transmittal and tax form collection.
This stockholder list should be provided to Calderwood & Harkness LLP at the earliest practicable date and in any event no later than fifteen (15) business days prior to the anticipated closing date.
9. Contact Information
For questions regarding this letter, the required tax certification forms, or the delivery process, please contact the following individuals at Calderwood & Harkness LLP:
Ryan Kowalski, Lead Associate (Mergers & Acquisitions) Telephone: (212) 558-4137
Email: ryan.kowalski@calderwoodharkness.com
Megan Chu, Working Associate (Mergers & Acquisitions) Telephone: (212) 558-4592
Email: megan.chu@calderwoodharkness.com
For tax-specific questions:
Sylvia Hartwell, Partner (Tax) Telephone: (212) 558-3021
Email: sylvia.hartwell@calderwoodharkness.com
We also note that the Buyer's independent accounting and tax advisor, Pendleton & Associates LLP (Richard Chow, Engagement Partner, 30 Rockefeller Plaza, Suite 2600, New York, NY 10112; telephone: (212) 489-7700; email: rchow@pendletonassociates.com), is available for consultation on matters relating to the purchase-price allocation, the potential Section 338(h)(10) election, and related transaction-level tax matters. However, each selling stockholder is strongly encouraged to consult its own independent tax advisor regarding the personal income tax consequences of the Merger, including the determination of gain or loss on the exchange of Company Common Stock for the Merger consideration, the availability of any applicable exemptions or treaty benefits, and the applicable state, local, and non-U.S. tax consequences of the transaction. Neither Calderwood & Harkness LLP, the Buyer, the Paying Agent, nor Pendleton & Associates LLP is providing tax advice to any selling stockholder, and nothing in this letter should be construed as tax advice to any party other than the Buyer.
10. Confidentiality Notice
This letter and the IRS Forms W-9, W-8BEN, W-8BEN-E, and other tax certification forms collected in response hereto contain sensitive taxpayer information that is protected under federal law, including Section 6103 of the Internal Revenue Code, which imposes strict confidentiality obligations with respect to tax return information and taxpayer identity information. The information collected in response to this letter will be used solely for the purposes of complying with the tax reporting and withholding obligations of the Paying Agent, the Buyer, and their authorized agents in connection with the Merger, and for no other purpose.
The information will be shared only with the following parties, to the extent necessary for the purposes described above:
(a) Atlas Shareholder Services Inc. (the Paying Agent);
(b) Ardent Apex Holdings Inc. (Parent) and its authorized representatives;
(c) Ardent Capital Partners III LP (the Buyer/Sponsor) and its authorized representatives;
(d) Calderwood & Harkness LLP (counsel to the Buyer);
(e) Pendleton & Associates LLP (tax advisor to the Buyer); and
(f) Such other agents or advisors as may be necessary to comply with applicable tax reporting and withholding obligations, subject to appropriate confidentiality protections.
No taxpayer information collected in response to this letter will be disclosed to any other party except as required by law or regulation or with the prior written consent of the applicable taxpayer.
We thank you in advance for your prompt cooperation and attention to this matter. The timely collection of the requested tax certification forms is a critical step in ensuring a smooth and efficient closing of the Merger and the prompt disbursement of the Merger consideration to all selling stockholders. Please do not hesitate to contact us with any questions.
Very truly yours,
CALDERWOOD & HARKNESS LLP
By: ________
Ryan Kowalski Associate 7 Times Square New York, NY 10036 Telephone: (212) 558-4137
Email: ryan.kowalski@calderwoodharkness.com
Enclosures:
1. IRS Form W-9 (Request for Taxpayer Identification Number and Certification) (Rev. current) — Blank
2. IRS Form W-8BEN (Certificate of Foreign Status of Beneficial Owner for United States Tax Withholding and Reporting — Individuals) (Rev. current) — Blank
3. IRS Form W-8BEN-E (Certificate of Status of Beneficial Owner for United States Tax Withholding and Reporting — Entities) (Rev. current) — Blank
4. Summary Instruction Sheet (prepared by Calderwood & Harkness LLP) — Identifying which form each category of selling stockholder should complete
cc: (via email)
James Prentice, Partner, Calderwood & Harkness LLP Sandra Tung, Partner, Calderwood & Harkness LLP Sylvia Hartwell, Partner, Calderwood & Harkness LLP Theodore "Ted" Hargrove, Ardent Capital Partners III LP, 399 Park Avenue, 42nd Floor, New York, NY 10022 Victoria Langford, Ardent Capital Partners III LP, 399 Park Avenue, 42nd Floor, New York, NY 10022 David Ng, CFO, Ardent Capital Partners III LP, 399 Park Avenue, 42nd Floor, New York, NY 10022 Richard Chow, Pendleton & Associates LLP, 30 Rockefeller Plaza, Suite 2600, New York, NY 10112 Patricia Okonkwo, Caldwell, Raines & Sheppard LLP, 51 West 52nd Street, New York, NY 10019 Daniel Feinberg, Caldwell, Raines & Sheppard LLP, 51 West 52nd Street, New York, NY 10019 Dennis Carmichael, Atlas Shareholder Services Inc., 6201 15th Avenue, Brooklyn, NY 11219 Laura Svensson, Continental Fiduciary Trust Company, 60 Wall Street, 24th Floor, New York, NY 10005 (for escrow-related coordination)
Stockholder | Title | Approx. % of Equity | Total Equity Value | Cash-Out Portion | Rollover Portion
Dr. Stefan Kessler | Chief Executive Officer | 8.5% | $238,000,000 | $95,200,000 (40%) | $142,800,000 (60%)
Annelise Gruber | Chief Financial Officer | 4.2% | $117,600,000 | $58,800,000 (50%) | $58,800,000 (50%)
Dr. Markus Vogt | Chief Technology Officer | 3.8% | $106,400,000 | $47,880,000 (45%) | $58,520,000 (55%)
Other management and employee holders | Various | 11.5% (aggregate) | $322,000,000 (aggregate) | ~$177,100,000 (aggregate) | ~$144,900,000 (aggregate)

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