STOCK TITAN

Seaport Therapeutics (SPTX) CMO gains common shares and 63,680-share option grant

Filing Impact
(Neutral)
Filing Sentiment
(Neutral)
Form Type
4

Rhea-AI Filing Summary

Seaport Therapeutics Chief Medical Officer Antony Loebel reported equity-related changes in his holdings. He converted 63,157 shares of Series B Preferred Stock into 20,109 shares of Common Stock on a one‑for‑3.1407 basis, tied to the closing of the company’s initial public offering, and now holds 20,109 common shares directly.

On a separate date, he received a stock option for 63,680 shares of Common Stock at an exercise price of $18.00 per share, expiring on April 29, 2036. These option shares vest in 48 equal monthly installments following April 30, 2026, contingent on his continued service, and represent compensation rather than open‑market trading.

Positive

  • None.

Negative

  • None.
Insider Loebel Antony
Role Chief Medical Officer
Type Security Shares Price Value
Conversion Series B Preferred Stock 63,157 $0.00 --
Conversion Common Stock 20,109 $0.00 --
Grant/Award Stock Option (Right to Buy) 63,680 $0.00 --
Holdings After Transaction: Series B Preferred Stock — 0 shares (Direct, null); Common Stock — 20,109 shares (Direct, null); Stock Option (Right to Buy) — 63,680 shares (Direct, null)
Footnotes (1)
  1. Each share of Series B Preferred Stock (the "Preferred Stock") was convertible into Common Stock of the Issuer on a one-for-3.1407 basis at the option of the holder, and automatically converted upon the closing of the Issuer's initial public offering without payment of further consideration. The Preferred Stock had no expiration date. The shares underlying this option shall vest in forty-eight (48) equal monthly installments following April 30, 2026, subject to the Reporting Person's continued service on each such vesting date.
Common shares acquired 20,109 shares Common Stock held directly after preferred conversion
Series B Preferred converted 63,157 shares Converted into 20,109 Common shares at one-for-3.1407
Stock option size 63,680 shares Stock Option (Right to Buy) granted April 30, 2026
Option exercise price $18.00 per share Conversion or exercise price for stock option
Option expiration April 29, 2036 Expiration date of 63,680-share stock option
Vesting schedule 48 monthly installments Option vests in equal installments after April 30, 2026
Exercise shares from conversion 63,157 shares ExerciseShares in transactionSummary for derivative conversion
Conversion of derivative security financial
"transaction_code_description: Conversion of derivative security"
Series B Preferred Stock financial
"security_title: Series B Preferred Stock"
Series B preferred stock is a type of ownership share issued by a company that offers certain advantages over common stock, such as priority in receiving dividends or assets if the company is sold or liquidated. It is typically issued after an initial round of funding, making it a way for investors to support a company's growth while gaining some protections and benefits. This stock matters to investors because it often provides a more secure investment position with potential for future growth.
Stock Option (Right to Buy) financial
"security_title: Stock Option (Right to Buy)"
initial public offering financial
"automatically converted upon the closing of the Issuer's initial public offering"
An initial public offering (IPO) is when a private company first sells its shares to the public and becomes a stock-listed company. It matters because it allows the company to raise money from a wide range of investors, helping it grow, while giving early shareholders a way to sell some of their ownership.
vesting financial
"shall vest in forty-eight (48) equal monthly installments"
Vesting is the process by which you earn full ownership of something, like company stock or a retirement benefit, over time. It’s like earning the right to keep a gift piece by piece the longer you stay with a company, making sure employees stay committed before they receive all the benefits.
SEC Form 4
FORM 4UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

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:3235-0287
Estimated average burden
hours per response:0.5
Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.
1. Name and Address of Reporting Person*
Loebel Antony

(Last)(First)(Middle)
SEAPORT THERAPEUTICS, INC.
101 SEAPORT BLVD., FLOOR 12

(Street)
BOSTON MASSACHUSETTS 02210

(City)(State)(Zip)

UNITED STATES

(Country)
2. Issuer Name and Ticker or Trading Symbol
Seaport Therapeutics, Inc. [ SPTX ]
5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
Director10% Owner
XOfficer (give title below)Other (specify below)
Chief Medical Officer
2a. Foreign Trading Symbol
3. Date of Earliest Transaction (Month/Day/Year)
04/30/2026
6. Individual or Joint/Group Filing (Check Applicable Line)
XForm filed by One Reporting Person
Form filed by More than One Reporting Person
4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year)2A. Deemed Execution Date, if any (Month/Day/Year)3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4)
CodeVAmount(A) or (D)Price
Common Stock05/04/2026C20,109A(1)20,109D
Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (Month/Day/Year)3A. Deemed Execution Date, if any (Month/Day/Year)4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 6. Date Exercisable and Expiration Date (Month/Day/Year)7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4)
CodeV(A)(D)Date ExercisableExpiration DateTitleAmount or Number of Shares
Stock Option (Right to Buy)$1804/30/2026A63,680 (2)04/29/2036Common Stock63,680$063,680D
Series B Preferred Stock(1)05/04/2026C63,157 (1) (1)Common Stock20,109$00D
Explanation of Responses:
1. Each share of Series B Preferred Stock (the "Preferred Stock") was convertible into Common Stock of the Issuer on a one-for-3.1407 basis at the option of the holder, and automatically converted upon the closing of the Issuer's initial public offering without payment of further consideration. The Preferred Stock had no expiration date.
2. The shares underlying this option shall vest in forty-eight (48) equal monthly installments following April 30, 2026, subject to the Reporting Person's continued service on each such vesting date.
/s/ Lana Gladstein, Attorney-in-Fact05/04/2026
** Signature of Reporting PersonDate
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.
* Form 4: SEC 1474 (03-26)

FAQ

What insider transactions did Seaport Therapeutics (SPTX) report for Antony Loebel?

Antony Loebel reported a preferred-to-common conversion and an option grant. He converted 63,157 Series B Preferred shares into 20,109 Common shares and received a stock option covering 63,680 Common shares as equity compensation.

How many Seaport Therapeutics (SPTX) common shares does Antony Loebel now hold?

Antony Loebel holds 20,109 shares of Seaport Therapeutics Common Stock. These shares resulted from converting 63,157 Series B Preferred shares into common at a one‑for‑3.1407 ratio in connection with the company’s initial public offering closing.

What are the key terms of Antony Loebel’s Seaport Therapeutics (SPTX) stock option grant?

Loebel received an option for 63,680 Seaport Therapeutics common shares. The option has an exercise price of $18.00 per share, expires on April 29, 2036, and vests in 48 equal monthly installments after April 30, 2026, subject to continued service.

Was there any open-market buying or selling by Antony Loebel in this Seaport Therapeutics (SPTX) Form 4?

The Form 4 shows no open-market purchases or sales. It reports a conversion of Series B Preferred Stock into Common Stock and a compensatory stock option grant, both classified as acquisition-type transactions rather than market trades.

How was Seaport Therapeutics (SPTX) Series B Preferred Stock converted in Antony Loebel’s filing?

Each share of Series B Preferred Stock converted into Common Stock on a one‑for‑3.1407 basis. The preferred shares automatically converted into 20,109 common shares upon closing of Seaport Therapeutics’ initial public offering, with no additional consideration required.

Over what period will Antony Loebel’s Seaport Therapeutics (SPTX) option shares vest?

The 63,680 option shares vest over 48 monthly installments. Vesting begins after April 30, 2026, with equal portions vesting each month, contingent on Antony Loebel’s continued service to Seaport Therapeutics on each vesting date.