# EDGAR Filing Document

**Accession Number:** 0002042347
**File Stem:** 0001193125-26-198501
**Filing Date:** 2026-4
**Character Count:** 8707
**Document Hash:** 5d17c307664efd2fcbb1b6105315d4d5
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001193125-26-198501.hdr.sgml**: 20260430

**ACCESSION NUMBER**: 0001193125-26-198501

**CONFORMED SUBMISSION TYPE**: 3

**PUBLIC DOCUMENT COUNT**: 2

**CONFORMED PERIOD OF REPORT**: 20260430

**FILED AS OF DATE**: 20260430

**DATE AS OF CHANGE**: 20260430

**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** Gladstein Lana
- **CENTRAL INDEX KEY:** 0002127496

**ORGANIZATION NAME:**

**FILING VALUES:**
- **FORM TYPE:** 3
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-43254
- **FILM NUMBER:** 26928311

**MAIL ADDRESS:**
- **STREET 1:** C/O SEAPORT THERAPEUTICS, INC.
- **STREET 2:** 101 SEAPORT BLVD. FLOOR 12
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02210
**ISSUER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Seaport Therapeutics, Inc.
- **CENTRAL INDEX KEY:** 0002042347
- **STANDARD INDUSTRIAL CLASSIFICATION:** PHARMACEUTICAL PREPARATIONS [2834]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 992235719
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**BUSINESS ADDRESS:**
- **STREET 1:** 6 TIDE STREET
- **STREET 2:** SUITE 400
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02110
- **BUSINESS PHONE:** 617-807-4062

**MAIL ADDRESS:**
- **STREET 1:** 6 TIDE STREET
- **STREET 2:** SUITE 400
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02110

## Ex-24

**Power of Attorney**

Know all by these presents that the undersigned hereby constitutes and appoints each of Lana Gladstein and Lauren White, and with full power of substitution, as the undersigned's true and lawful attorney-in-fact to:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;a)execute for and on behalf of the undersigned, in the undersigned's capacity as an officer of Seaport Therapeutics, Inc., a Delaware corporation (the "Company"), Forms 3, 4, and *5* in accordance with Section I6(a) of the Securities Exchange Act of 1934, as amended, and the rules thereunder;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;b)do and perform any and all acts for and on behalf of the undersigned which may be necessary or desirable to complete and execute any such Form 3, 4, or *S,* complete and execute any amendment or amendments thereto, and timely file such fonn with the SEC and any stock exchange or similar authority; and

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;c)take any other action of any type whatsoever in connection with the foregoing which, in the opinion of such attorney-in-fact, may be of benefit to, in the best interest of, or legally required by, the undersigned, it being understood that the documents executed by such attorney-in-fact on behalf of the undersigned pursuant to this Power of Attorney shall be in such form and shall contain such terms and conditions as such attorney• in-fact may approve in such attorney-in-fact's discretion.

The undersigned hereby grants to each such attorney-in-fact full power and authority to do and perform any and every act and thing whatsoever requisite, necessary, or proper to be done in the exercise of any of the rights and powers herein granted, as fully to all intents and purposes as the undersigned might or could do if personally present, with full power of substitution or revocation, hereby ratifying and confirming all that such attorney-in-fact, or such attorney-in-fact's substitute or substitutes, shall lawfully do or cause to be done by virtue of this power of attorney and the rights and powers herein granted. The undersigned acknowledges that the foregoing attorneys-in-fact, in serving in such capacity at the request of the undersigned, is not assuming, nor is the Company assuming, any of the undersigned's responsibilities to comply with Section 16 of the Securities Exchange Act of I934, as amended.

This Power of Attorney shall remain in full force and effect until the undersigned is no longer required to file Forms 3, 4, and 5 with respect to the undersigned's holdings of and transactions in securities issued by the Company, unless earlier revoked by the undersigned in a signed writing delivered to the foregoing attorneys-in-fact.

IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be executed as of this day of March 24, 2026

---

| |
|:---|
| /s/ Lana Gladstein |
| &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <br>Name: Lana Gladstein |

---

------

### UNITED STATES SECURITIES AND EXCHANGE COMMISSION
**Washington, D.C. 20549**

## FORM 3

### INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

[ ] Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

---

| | | |
|:---|:---|:---|
| **1. Name and Address of Reporting Person**<sup>*</sup><br>Gladstein Lana<br><sub>(Last) (First) (Middle)</sub><br>SEAPORT THERAPEUTICS, INC.<br>101 SEAPORT BLVD., FLOOR 12<br><sub>(Street)</sub><br>BOSTON, MA 02210<br><sub>(City) (State) (Zip)</sub> | **3. Issuer Name and Ticker or Trading Symbol**<br>Seaport Therapeutics, Inc. [ SPTX ] | **5. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  |
| **2. Date of Event Requiring Statement (Month/Day/Year)**<br>2026-04-30 | **4. Relationship of Reporting Person(s) to Issuer**<br>(Check all applicable)<br>[ ] Director   [ ] 10% Owner<br>[X] Officer (give title below)   [ ] Other (specify below)<br>_General Counsel_ | **6. Individual or Joint/Group Filing (Check Applicable Line)**<br>[X] Form filed by One Reporting Person<br>[ ] Form filed by More than One Reporting Person |

---

## Table I - Non-Derivative Securities Beneficially Owned

---

|  |  |  |  |
| --- | --- | --- | --- |
| 1. Title of Security | 2. Amount of Securities Beneficially Owned | 3. Ownership Form | 4. Nature of Indirect Beneficial Ownership |

---

## Table II - Derivative Securities Beneficially Owned

---

|  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- |
| 1. Title of Derivative Security | 2. Date Exercisable and Expiration Date (Month/Day/Year) | 2. Date Exercisable and Expiration Date (Month/Day/Year) | 3. Title and Amount of Underlying Securities | 3. Title and Amount of Underlying Securities | 4. Conversion or Exercise Price | 5. Ownership Form | 6. Nature of Indirect Beneficial Ownership |
| 1. Title of Derivative Security | Date Exercisable | Expiration Date | Title | Amount or Number of Shares | 4. Conversion or Exercise Price | 5. Ownership Form | 6. Nature of Indirect Beneficial Ownership |
| Series B Preferred Stock | <sup>(1)</sup> | <sup>(1)</sup> | Common Stock | 33515 | <sup>(1)</sup> | D |  |
| Stock Option (Right to Buy) | <sup>(2)</sup> | 2034-06-03 | Common Stock | 246760 | $3.05 | D |  |
| Stock Option (Right to Buy) | <sup>(3)</sup> | 2034-12-28 | Common Stock | 26533 | $7.39 | D |  |
| Stock Option (Right to Buy) | <sup>(4)</sup> | 2036-02-23 | Common Stock | 63680 | $10.31 | D |  |

---

### Footnotes:

(1) Each share of Series B Preferred Stock (the "Preferred Stock") is convertible into Common Stock of the Issuer on a one-for-3.1407 basis at the option of the holder, and will automatically convert upon the closing of the Issuer's initial public offering into the number of shares shown in Column 3 without payment of further consideration. The Preferred Stock has no expiration date.

(2) 1/4th of the shares underlying this option vested and became exercisable on June 6, 2025, with the remaining shares vesting in thirty-six (36) equal monthly installments thereafter, subject to the Reporting Person's continued service on each vesting date.

(3) The shares underlying this option are fully vested and exercisable.

(4) The shares underlying this option shall vest in forty-eight (48) equal monthly installments following February 24, 2026, subject to the Reporting Person's continued service on each such vesting date.

**Remarks:**
Exhibit 24 - Power of Attorney

**Signature:** /s/ Lana Gladstein  
**Date:** 2026-04-30

### Remarks:

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.

**Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.**