Seaport Therapeutics (SPTX) director Sharon Mates submits initial Form 3

Rhea-AI Filing Summary

Seaport Therapeutics, Inc. director Sharon Mates has filed an initial Form 3 insider ownership report. The provided data show no reported transactions and no derivative positions, indicating this filing is primarily an administrative disclosure of insider status rather than a record of trading activity.

Key Figures

Net buy/sell shares: 0 shares Buy transactions: 0 Sell transactions: 0

3 metrics

Net buy/sell shares 0 shares Form 3 transaction summary

Buy transactions 0 Form 3 transactionSummary buyCount

Sell transactions 0 Form 3 transactionSummary sellCount

Key Terms

Form 3, reporting person, derivative positions

3 terms

Form 3 regulatory

"INSIDER FILING DATA (Form 3):"

Form 3 is the initial public filing that officers, directors and large shareholders must submit to report their ownership of a company’s securities when they become insiders. It acts like an opening inventory sheet that gives investors a starting point to see who holds significant stakes and to spot later trades or potential conflicts of interest, helping assess insider confidence and transparency.

reporting person regulatory

""reportingPersons": [ { "name": "Mates Sharon""

derivative positions financial

""derivativeSummary": [],"

Derivative positions are contracts that derive their value from an underlying asset—such as a stock, bond, currency or commodity—and include instruments like options, futures and swaps. Think of them as bets or insurance tied to an asset’s future price: they let investors amplify returns, hedge risk or take exposure without owning the asset directly, which can meaningfully increase potential gains, losses and volatility in a portfolio.

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SEC Form 3

FORM 3

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

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0104
Estimated average burden
hours per response:			0.5

1. Name and Address of Reporting Person^*

Mates Sharon

(Last) (First) (Middle)

SEAPORT THERAPEUTICS, INC.

101 SEAPORT BLVD., FLOOR 12

(Street)

BOSTON MASSACHUSETTS 02210

(City) (State) (Zip)

UNITED STATES

(Country)

2. Date of Event Requiring Statement (Month/Day/Year)
04/30/2026

3. Issuer Name and Ticker or Trading Symbol
Seaport Therapeutics, Inc. [ SPTX ]

3a. Foreign Trading Symbol

5. If Amendment, Date of Original Filed (Month/Day/Year)

4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
	Officer (give title below)		Other (specify below)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

Remarks:

Exhibit 24 - Power of Attorney

No securities are beneficially owned.

	/s/ Lana Gladstein, Attorney-in-Fact	04/30/2026
	** Signature of Reporting Person	Date
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 5 (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.
* Form 3: SEC 1473 (03-26)

FAQ

What does Sharon Mates’ Form 3 filing for SPTX show?

The Form 3 filing for Seaport Therapeutics (SPTX) lists director Sharon Mates as a reporting person. The transaction summary shows no buy, sell, exercise, gift, or restructuring activity and no derivative positions in the data provided.

Are there any insider share purchases or sales in this SPTX Form 3?

No insider purchases or sales are shown. The transaction summary reports 0 buy and 0 sell transactions, with netBuySellShares listed as 0, indicating no trading activity in the provided Form 3 data.

Does the SPTX Form 3 show any option or derivative exercises?

No derivative exercises are indicated. The summary lists an exerciseCount of 0 and derivativeTransactionCount of 0, and the derivativeSummary is empty, suggesting no options or similar derivatives are reported in this Form 3 excerpt.

What role does Sharon Mates have at Seaport Therapeutics (SPTX)?

Sharon Mates is identified as a director of Seaport Therapeutics, Inc. in the Form 3 data. She is not flagged as an officer or a ten percent owner in the provided structured information.

Does this SPTX Form 3 include any gifts or tax-withholding transactions?

No gifts or tax-withholding events are shown. The filing’s transaction summary lists giftCount and taxWithholdingCount as 0, with corresponding share counts also at 0, indicating no such transactions in this Form 3 data.