Contract analysis

I. Executive Summary This memorandum analyzes the Section 16(a) reporting obligations arising under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), in connection with the dispositions of shares of common stock of Penterra Pharmaceuticals Corp. ("PPC" or the "Company") (Nasdaq: PNTR; SEC CIK No. 0001987654) by three insiders of the Company who are selling stockholders in PPC's registered selling-

II. Background A. The Offering Penterra Pharmaceuticals Corp. is a Delaware corporation headquartered at 400 Meridian Parkway, Suite 1200, Princeton, New Jersey 08540. PPC's common stock is listed and publicly traded on the Nasdaq Global Select Market under the ticker symbol "PNTR." The Company is a clinical-stage biopharmaceutical company focused on the development of novel therapeutics for rare metabolic and neurol

III. Section 16(a) Reporting Requirements — Legal Framework A. Statutory and Regulatory Basis

Section 16(a) of the Securities Exchange Act of 1934 (15 U.S.C. § 78p(a)) imposes reporting obligations on certain insiders of issuers that have a class of equity securities registered under Section 12 of the Exchange Act. Specifically, Section 16(a) requires every person who is a director, an officer (as defined in Rule 16a-1(f) under the Exchange Act), or a beneficial owner of more than ten percent (10%) of a class

IV. Filing Deadline Calculation A. Computation of Two-Business-Day Deadline The filing deadline for Form 4 is calculated by reference to the execution date of the transaction, in accordance with Rule 16a-3(g) under the Exchange Act. The relevant computation is as follows: Transaction Execution Date: Thursday, October 12, 2023 Business Day 1: Friday, October 13, 2023 Non-Business Days: Saturday, October 14, 2023, and

V. Special Considerations — Castellano Family Holdings LLC A. Beneficial Ownership Attribution Castellano Family Holdings LLC is a Delaware limited liability company that is selling 250,000 shares of PPC common stock in the base offering and has committed up to 37,500 additional shares subject to the over-allotment option. CFH LLC is not itself a director or officer of PPC and does not independently qualify as a Sect

VI. Form 4 Content — Summary for Each Reporting Person Set forth below is a summary of the key content to be included in each of the three Form 4 filings. Draft Form 4s in EDGAR-ready XML format will be prepared by Brendan Walsh and Audrey Zhou and circulated under separate cover. A. Dr. Elena Castellano — Form 4 Issuer Name: Penterra Pharmaceuticals Corp. Issuer Ticker Symbol: PNTR Issuer CIK Number: 0001987654 Repo

VII. Over-Allotment Option — Contingent Additional Filings The selling stockholders have granted the underwriters a 30-day over-allotment option, exercisable in whole or in part at any time through November 11, 2023 (30 calendar days from the October 12, 2023 pricing date), to purchase up to 937,500 additional shares of PPC common stock. The over-allotment option was granted pursuant to the terms of the Underwriting

VIII. Section 16(b) Short-Swing Profit Considerations Although the primary focus of this memorandum is the Section 16(a) reporting obligations, we also briefly address Section 16(b) short-swing profit considerations to confirm that the dispositions in the Offering do not give rise to potential short-swing profit liability.

Section 16(b) of the Exchange Act provides for the disgorgement of any profit realized by a director, officer, or greater-than-10% beneficial owner from any purchase and sale, or sale and purchase, of the issuer's equity securities within a period of less than six months. The statute imposes strict liability; intent to profit from inside information is not required. Any "profit" realized within the six-month window i

IX. Action Items and Next Steps The following action items should be completed in connection with the Form 4 filings and related matters:

1. Brendan Walsh / Audrey Zhou: Prepare draft Form 4s for each of the three reporting persons (Dr. Elena Castellano, Dr. Riccardo Castellano, and Dr. Marco Castellano) in EDGAR-ready format and circulate internally to Jennifer Kwon for review and approval. Target completion: end of day, Friday, October 13, 2023.

2. Jennifer Kwon: Review and approve draft Form 4s. Target completion: Saturday, October 14, 2023.

3. Brendan Walsh: Circulate approved Form 4 drafts to David Orenstein (PPC General Counsel and Corporate Secretary) and Patricia Velázquez (Whitfield & Garza LLP, selling stockholders' personal counsel) for review and sign-off by the respective reporting persons. Target completion: no later than Sunday, October 15, 2023.

4. David Orenstein / PPC: Arrange for the electronic filing of all three Form 4s via the SEC's EDGAR system no later than 10:00 p.m. Eastern Time on Monday, October 16, 2023. Recommend targeting filing by 5:00 p.m. ET to allow buffer for any EDGAR technical issues.

5. Brendan Walsh: Confirm the governance structure of Castellano Family Holdings LLC (specifically, voting and investment control over PPC shares) with Patricia Velázquez at Whitfield & Garza LLP and with David Orenstein, to finalize the indirect ownership reporting analysis and complete the Form 4 drafts for Dr. Elena Castellano and Dr. Riccardo Castellano. Target completion: Saturday, October 14, 2023.

6. Brendan Walsh: Confirm with David Orenstein the absence of any Section 16(b)-triggering transactions (purchases, option exercises, RSU vestings, or other acquisitions) by any of the three reporting persons during the six-month lookback period (April 12, 2023 to October 12, 2023). Target completion: no later than Monday, October 16, 2023.

7. Audrey Zhou: Prepare contingent over-allotment Form 4 drafts for each reporting person, reflecting the additional dispositions that would result from exercise of the over-allotment option. Hold drafts in reserve until exercise notice is received from Ridgeline Securities LLC. Target completion of drafts: Friday, October 20, 2023.

8. All (ongoing through November 11, 2023): Monitor the status of the over-allotment option through the November 11, 2023 exercise deadline. Primary contact: Angela Ferris, Ridgeline Securities LLC (syndicate desk). If the over-allotment is exercised in whole or in part, file additional Form 4s within two business days of the exercise date. Coordinate with David Orenstein and the PPC in-house team for EDGAR filing.

X. Appendix Appendix A — Summary Table of Filing Deadlines Note: Filing deadline is the second business day after the transaction execution date. All filings must be submitted via EDGAR before 10:00 p.m. ET on October 16, 2023. Over-allotment dispositions, if any, will be subject to separate Form 4 filing deadlines calculated from the over-allotment exercise date. Appendix B — Key Reference Information Issuer: Penter