Daniel D. Long - 03 Aug 2026 Form 4 Insider Report for Septerna, Inc. (SEPN)

Reporting relationship: SVP, Drug Discovery
Issuer ticker: SEPN
Reported as of: 03 Aug 2026
Net transaction value: -$114,920
SEC form: 4
Accepted by SEC: 05 Aug 2026, 19:00:03 UTC
Prior SEC filing: 02 Jul 2026
Source filing: View source filing
Reporting owner signature: /s/ Mark A. Wilson, Attorney-in-Fact

Key filing fact

Daniel D. Long filed Form 4 for Septerna, Inc. (SEPN) on 05 Aug 2026.

Key facts

This page summarizes Daniel D. Long's Form 4 filing for Septerna, Inc. (SEPN).
6 reported transactions and 2 derivative rows are listed below.
Accepted by SEC: 05 Aug 2026, 19:00.

Change

Previous filing in this sequence was filed on 02 Jul 2026.
Current net transaction value: -$114,920.

Research use

This tells you what this filing adds before you inspect full transaction and derivative tables.
You can trace every row back to the original SEC filing document.

Evidence

Filed on Form 4

Ownership activity is grounded in SEC Form 4 disclosures.

View source filing

Reporting Owners (1)

CIK 0002040349 Primary reporting owner

Long Daniel D.

Relationship: SVP, Drug Discovery
Address: C/O SEPTERNA, INC., 250 EAST GRAND AVENUE, SOUTH SAN FRANCISCO
Signature: /s/ Mark A. Wilson, Attorney-in-Fact
Signature date: 05 Aug 2026

Reported non-derivative transactions

Shares, units, or other non-derivative securities reported in this filing.

SEPN transaction

Common Stock

Options Exercise

Transaction value
Shares: +1,816
Change %: +1.9%
Price: $2.76^*
Shares after: 98,228
Date: 03 Aug 2026
Ownership: Direct

SEPN transaction

Common Stock

Options Exercise

Transaction value
Shares: +1,518
Change %: +1.5%
Price: $2.76^*
Shares after: 99,746
Date: 03 Aug 2026
Ownership: Direct

SEPN transaction

Common Stock

Sale

Transaction value: $33,976
Shares: -1,000
Change %: -1%
Price: $33.98
Shares after: 98,746
Date: 03 Aug 2026
Ownership: Direct
Footnotes: F1, F2

SEPN transaction

Common Stock

Sale

Transaction value: $80,944
Shares: -2,334
Change %: -2.4%
Price: $34.68
Shares after: 96,412
Date: 03 Aug 2026
Ownership: Direct
Footnotes: F1, F3

Reported derivative securities

Options, warrants, convertible securities, or similar derivative positions disclosed in the filing.

SEPN transaction Derivative

Stock Option (Right to Buy)

Options Exercise

Transaction value
Shares: -1,816
Change %: -26%
Price: $0.000000^*
Shares after: 5,227
Date: 03 Aug 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 1,816
Exercise price: $2.76
Footnotes: F4

SEPN transaction Derivative

Stock Option (Right to Buy)

Options Exercise

Transaction value
Shares: -1,518
Change %: -11%
Price: $0.000000^*
Shares after: 12,418
Date: 03 Aug 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 1,518
Exercise price: $2.76
Footnotes: F5

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Rule 10b5-1 trading plan

These transactions were reported as open-market trades under a Rule 10b5-1 plan. The plan lets an insider set trading instructions in advance, which can reduce the risk of trading while in possession of material nonpublic information.

Original filing language: transaction made pursuant to a contract, instruction, or written plan intended to satisfy Rule 10b5-1(c).

Explanation of responses 5 footnotes

Footnote F1

This transaction was effected pursuant to a Rule 10b5-1 sales plan adopted by the Reporting Person on March 20, 2026.

Footnote F2

The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $33.39 to $34.32. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

Footnote F3

The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $34.43 to $35.04. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

Footnote F4

1/48th of the shares subject to such option shall vest and become exercisable in substantially equal monthly installments on each monthly anniversary of August 1, 2023, subject to the Reporting Person's continuous service to the Issuer on each such date.

Footnote F5

1/48th of the shares subject to such option shall vest and become exercisable in substantially equal monthly installments on each monthly anniversary of March 1, 2024, subject to the Reporting Person's continuous service to the Issuer on each such date.