Seaport Therapeutics, Inc. - Voting Common Stock, $0.001 par value per share (SPTX)

Q: What does CUSIP 81221K108 represent in this 13F holders report?

CUSIP 81221K108 is the security identifier for SPTX - Seaport Therapeutics, Inc. - Voting Common Stock, $0.001 par value per share used to aggregate holder disclosures.

Q: How many institutions held SPTX - Seaport Therapeutics, Inc. - Voting Common Stock, $0.001 par value per share in Q3 2026?

3 institutional investors reported SPTX - Seaport Therapeutics, Inc. - Voting Common Stock, $0.001 par value per share for Q3 2026. Use the holders table for investor-level position and value details.

CUSIP: 81221K108

Q3 2026 13F Holders as of 30 Sep 2026

Security type / class: Equity / Voting Common Stock, $0.001 par value per share
Total 13F shares: 2,492
Total 13F value: $50,263
Share change: +1,061
SEC-reported price per share: $20.17
Number of holders: 3
Value change: +$21,400
Number of buys: 3
Shares outstanding: 53,477,606

Security key

81221K108

Report period

Q3 2026

Institutions

Top holders

SPTX full security history Ownership snapshot Full 13F holder table Previous quarter: Q2 2026 Seaport Therapeutics, Inc. SEC filings Seaport Therapeutics, Inc. company facts

Broader feeds

Latest 13F filings Latest 13D/G filings Investors directory

Reporting periods

Holder history for CUSIP 81221K108

Previous quarter: Q2 2026

Recent filing periods:

Q3 2026 Q2 2026

Ownership snapshot

Top reported holders of SPTX - Seaport Therapeutics, Inc. - Voting Common Stock, $0.001 par value per share (13F + 13D/G + 3/4/5)

Grouped by holder across the latest SEC ownership disclosures. Start with comparable ownership when available, then verify the linked 13F, 13D/G, or 3/4/5 evidence.

Comparable stake leader

PureTech LYT, Inc.

Disclosed value leader

PureTech LYT, Inc.

Comparable rows

3/15

Latest evidence

30 Jun 2026

13D/G 3/4/5 13F Lead comparable stake: 31% 12 rows are not safely comparable across share classes. 13D/G row: PureTech LYT, Inc. Showing 1-6 of 15 holder rows.

Quick read

PureTech LYT, Inc. leads the comparable SEC ownership view at 31%.

3 of 15 rows have a safely comparable ownership percentage. Use this as a filing-backed starting point, then open the detailed table for source links, reporting role, position value, share count, and filing date.

Open SEC evidence Opens PureTech LYT, Inc.'s linked filing trail.

Comparable ownership Top 3

PureTech LYT, Inc. 31%

Zohar Daphne 9.1%

Steven M. Paul 6.3%

Ownership % is shown only when SEC disclosures are safely comparable across share classes.

Detailed SEC evidence table Showing 1-6 of 15 holder rows

Holder	Evidence	Ownership %	Position	12M Net Δ	As of
PureTech LYT, Inc.	13D/G 3/4/5 PureTech Health plc · 10%+ Owner 13D/G 3/4/5	31% Reported 13D/G · 30 Jun 2026	$335,368,761 16,685,013 shares	$0	30 Jun 2026
Zohar Daphne	13D/G 3/4/5 Chief Executive Officer, Director 13D/G 3/4/5	9.1% Reported 13D/G · 30 Jun 2026	$105,032,490 5,225,497 shares	$0	30 Jun 2026
Steven M. Paul	13D/G 3/4/5 PAUL STEVEN M · Director 13D/G 3/4/5	6.3% Reported 13D/G · 30 Jun 2026	$70,686,032 3,516,718 shares	$0	30 Jun 2026
GENERAL ATLANTIC, L.P.	13F 3/4/5 Company · Director, 10%+ Owner 13F 3/4/5	— denominator unverified	$132,526,361 6,101,582 shares	—	30 Jun 2026
PureTech Health plc	3/4/5 10%+ Owner 3/4/5	— denominator unverified	— 16,685,013 shares	—	04 May 2026
ARCH Venture Fund XII, L.P.	3/4/5 10%+ Owner 3/4/5	— denominator unverified	— 6,294,951 shares	—	04 May 2026

How to read this table

Rows are grouped by holder and ranked first by SEC-reported ownership % when it is safely comparable, then by disclosed holdings value. — indicates unavailable or non-comparable values; "mixed-class rows" means the latest filing spans non-comparable classes.

13F holder rows

Institutional holders as of Q3 2026

Investor-level positions for this CUSIP, loaded as an interactive table.

Institutions

2,492

Rows available

Investor	Option	Weight %	Change %	SEC-reported value	* Price	Shares	Share Change	Activity	Report Period

^* SEC-reported price is the security price as of the portfolio date and can indicate the last known price at which the security was still held. The marker flags a reported price that did not pass the local price check.

Compare Q3 2026 vs Q2 2026 Across Filers

Q2 2026 holders

Q3 2026 holders

Holder diff

-51

Investor	Q2 2026 Shares	Q3 2026 Shares	Share Diff	Share Chg %	Q2 2026 value	Q3 2026 value	Value change	Value Chg %

Trend: ostatnie 8 kwartałów (+ wybrane okresy porównania).

Quarterly Holders Trend

Quarterly Value Trend

Quarterly Shares Trend