Seaport Therapeutics (SPTX) CMO reports option grants and Series B preferred stake

Filing Impact

(Neutral)

Filing Sentiment

(Neutral)

Form Type

Rhea-AI Filing Summary

Seaport Therapeutics, Inc. Chief Medical Officer Antony Loebel filed an initial Form 3 showing his derivative and preferred equity interests in the company. He holds stock options over 63,680 shares of common stock at an exercise price of $10.3100 per share, 5,306 shares at $7.3900, and 539,293 shares at $3.0500, all held directly. The filing also reports 20,109 shares of Series B Preferred Stock, which are convertible into common stock on a one-for-3.1407 basis and will automatically convert into the number of shares shown upon the closing of the company’s initial public offering without further payment. Footnotes explain that one option grant vests 25% on July 18, 2025 with the remainder in 36 equal monthly installments, another is fully vested and exercisable, and a third vests in 48 equal monthly installments following February 24, 2026, all subject to his continued service.

Insider Trade Summary

4 transactions reported

Mixed 4 txns

Insider Loebel Antony

Role Chief Medical Officer

Type	Security	Shares	Price	Value
holding	Series B Preferred Stock	--	--	--
holding	Stock Option (Right to Buy)	--	--	--
holding	Stock Option (Right to Buy)	--	--	--
holding	Stock Option (Right to Buy)	--	--	--

Holdings After Transaction: Series B Preferred Stock — 20,109 shares (Direct, null); Stock Option (Right to Buy) — 539,293 shares (Direct, null)

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. 1/4th of the shares underlying this option vested and became exercisable on July 18, 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. The shares underlying this option are fully vested and exercisable. 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.

Key Figures

Option underlying shares: 63,680 shares Option underlying shares: 5,306 shares Option underlying shares: 539,293 shares +4 more

7 metrics

Option underlying shares 63,680 shares Stock option, exercise price $10.3100/share

Option underlying shares 5,306 shares Stock option, exercise price $7.3900/share

Option underlying shares 539,293 shares Stock option, exercise price $3.0500/share

Preferred underlying shares 20,109 shares Series B Preferred Stock, convertible into common

Conversion ratio 1 : 3.1407 Series B Preferred to Common Stock

Vesting start date July 18, 2025 25% vests, then 36 monthly installments

Vesting schedule 48 monthly installments Option vesting following February 24, 2026

Key Terms

Stock Option (Right to Buy), Series B Preferred Stock, convertible into Common Stock, vesting, +1 more

5 terms

Stock Option (Right to Buy) financial

"security_title: "Stock Option (Right to Buy)""

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.

convertible into Common Stock financial

"is convertible into Common Stock of the Issuer on a one-for-3.1407 basis"

vesting financial

"shares underlying this option vested and became exercisable on July 18, 2025, with the remaining shares vesting in thirty-six"

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.

fully vested and exercisable financial

"The shares underlying this option are fully vested and exercisable."

See more from StockTitan in Google Search and AI answers. Adds StockTitan as a preferred source · opens Google

Add on Google

Understanding Insider Trading Forms →

04/30/2026 - 08:04 PM

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^*

Loebel Antony

(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)

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

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)
1. Title of Derivative Security (Instr. 4)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	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)
Series B Preferred Stock	⁽¹⁾	⁽¹⁾	Common Stock	20,109	⁽¹⁾	D
Stock Option (Right to Buy)	⁽²⁾	08/11/2034	Common Stock	539,293	$3.05	D
Stock Option (Right to Buy)	⁽³⁾	12/28/2034	Common Stock	5,306	$7.39	D
Stock Option (Right to Buy)	⁽⁴⁾	02/23/2036	Common Stock	63,680	$10.31	D

Explanation of Responses:

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 July 18, 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

	/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)

Source: View Original Filing on SEC EDGAR

FAQ

What does Seaport Therapeutics (SPTX) CMO Antony Loebel report on this Form 3?

Antony Loebel reports his initial ownership of Seaport Therapeutics derivatives and preferred stock. He holds several stock option grants over common shares and a position in Series B Preferred Stock that is convertible into common stock, outlining his equity-based economic interest.

How many Seaport Therapeutics (SPTX) shares are covered by Antony Loebel’s stock options?

The filing shows options over 63,680, 5,306 and 539,293 underlying common shares. Each grant has its own exercise price and vesting schedule, indicating multiple equity awards tied to his role as Chief Medical Officer at Seaport Therapeutics.

What are the exercise prices of Antony Loebel’s Seaport Therapeutics (SPTX) stock options?

Antony Loebel’s options have exercise prices of $10.3100, $7.3900 and $3.0500 per share. These prices represent the cost per share to acquire Seaport Therapeutics common stock upon exercising each respective option grant disclosed.

How is Seaport Therapeutics (SPTX) Series B Preferred Stock held by Antony Loebel convertible?

Each share of Series B Preferred Stock is convertible into Seaport Therapeutics common stock on a one-for-3.1407 basis. It will automatically convert into the number of common shares shown upon the closing of the company’s initial public offering without additional consideration.

What vesting terms apply to Antony Loebel’s Seaport Therapeutics (SPTX) stock options?

One option vests 25% on July 18, 2025 with the remainder in 36 equal monthly installments. Another grant is fully vested, while a third vests in 48 equal monthly installments after February 24, 2026, all contingent on his continued service.

Does this Seaport Therapeutics (SPTX) Form 3 show any stock purchases or sales?

The Form 3 presents Antony Loebel’s existing derivative and preferred holdings, not purchases or sales. Transactions are classified as holdings with unknown transaction codes, functioning as a baseline disclosure of his equity-related interests in Seaport Therapeutics.