Dear Working Group,
We are pleased to confirm that the selling-stockholder secondary offering of shares of common stock of Penterra Pharmaceuticals Corp. (Nasdaq: PNTR) has successfully closed and settled as of today, October 17, 2023 (T+3, with trade date of October 12, 2023), pursuant to the Underwriting Agreement dated October 12, 2023 among Penterra Pharmaceuticals Corp., the selling stockholders named therein, and the underwriters (Ridgeline Securities LLC, as representative of the several underwriters, Broadmark Capital Inc., Linden Groves & Co., and Harborview Partners LLC).
Set forth below is a summary of the transaction, deliverables status, funds flow, and next steps.
---
**A. Transaction Summary**
- **Securities Offered:** 6,250,000 shares of common stock, par value $0.001 per share - **Public Offering Price:** $41.60 per share - **Aggregate Offering Proceeds:** $260,000,000 - **Underwriting discount:** 2.50% ($1.04 per share); total underwriting commission of $6,500,000 - **Net Proceeds to Selling Stockholders (Base Offering):** $253,500,000 ($40.56 per share) - **Selling Stockholders:** - Dr. Elena Castellano — 3,000,000 shares - Dr. Riccardo Castellano — 2,500,000 shares - Dr. Marco Castellano — 500,000 shares - Castellano Family Holdings LLC — 250,000 shares - **Issuer Proceeds:** Penterra Pharmaceuticals Corp. is not selling any shares and will not receive any proceeds from the offering. - **Registration:** Shelf takedown under Form S-3 (File No. 333-274851); final prospectus supplement filed pursuant to Rule 424(b)(5) on October 12, 2023.
---
**B. Closing Deliverables — All Received and Confirmed**
We confirm that all closing deliverables required under the Underwriting Agreement have been received and/or delivered, including the following:
1. Executed Underwriting Agreement (dated October 12, 2023) 2. Officer's Certificate of Penterra Pharmaceuticals Corp. — signed by Dr. Marco Castellano (Chief Executive Officer) and Lisa Hargrove (Chief Financial Officer) 3. Secretary's Certificate of Penterra Pharmaceuticals Corp. — signed by David Orenstein (General Counsel & Corporate Secretary), with attached certificate of incorporation, bylaws, and board resolutions (adopted September 8, 2023) 4. Good Standing Certificate for Penterra Pharmaceuticals Corp. from the Delaware Secretary of State (dated October 16, 2023) 5. Issuer's Counsel Legal Opinion of Calderwood & Harkness LLP (validity opinion) 6. Issuer's Counsel Negative Assurance (10b-5) Letter of Calderwood & Harkness LLP 7. Comfort Letter and Bring-Down Comfort Letter of Graystone & Whitmore LLP (each dated as of October 17, 2023) 8. Selling Stockholder Representation Letters (dated October 12, 2023) 9. Selling Stockholder Certificates (dated October 17, 2023, executed by David Orenstein as attorney-in-fact) 10. Selling Stockholder Powers of Attorney and Custody Agreements 11. Lock-Up Waiver Consents from all three IPO underwriters (Ridgeline Securities LLC, Broadmark Capital Inc., and Morningstar Zanthor & Co.) — received September 29, 2023 12. New 90-Day Lock-Up Agreements executed by the selling stockholders in favor of the representatives 13. Transfer Agent Direction Letter to Pinnacle Trust & Transfer Co. 14. DTC Book-Entry Delivery of 6,250,000 shares confirmed (CUSIP 70831X 10 5)
---
**C. Funds Flow Confirmation**
Net proceeds of **$253,500,000** have been disbursed to the selling stockholders in accordance with the terms of the Underwriting Agreement and the Custody Agreements.
Total underwriting commissions of **$6,500,000** have been retained by the underwriters, allocated as follows:
| Underwriter
---
**D. Reminders / Next Steps**
1. **Over-Allotment Option.** The selling stockholders have granted the underwriters a 30-day option (expiring November 11, 2023) to purchase up to an additional 937,500 shares of common stock at the public offering price less the underwriting discount. If exercised, the over-allotment closing is expected to occur on or about November 16, 2023. We will circulate separate documentation in connection with any exercise.
2. **Section 16 Form 4 Filings.** Form 4s for Dr. Elena Castellano, Dr. Riccardo Castellano, and Dr. Marco Castellano are due within two business days of the trade date (i.e., by October 16, 2023). Brendan Walsh at Calderwood & Harkness is coordinating these filings. Please direct any questions regarding Section 16 compliance to Brendan directly.
3. **New 90-Day Lock-Up.** The selling stockholders are subject to a new 90-day lock-up period running from today, October 17, 2023, through and including January 15, 2024, covering all retained shares of common stock. Please ensure that the selling stockholders and their respective advisors are aware of this restriction.
4. **Form 8-K.** A Current Report on Form 8-K regarding entry into the Underwriting Agreement is to be filed/confirmed filed with the SEC. David and Lisa — please confirm when this has been completed if not already done.
---
**E. Closing Binder**
Brendan Walsh is preparing the closing index and comprehensive closing document binder. We anticipate circulating the final closing binder to all parties on or before October 27, 2023.
---
Congratulations to the full working group on bringing this transaction to a smooth and timely close. We appreciate everyone's efforts and responsiveness throughout the process.
Please do not hesitate to reach out to me or Brendan Walsh with any questions.
Best regards,
**Audrey Zhou** Senior Associate, Capital Markets Calderwood & Harkness LLP One Liberty Plaza, 52nd Floor New York, NY 10006 T: (212) 455-7832 E: azhou@calderwoodharkness.com