[Form 4] Septerna, Inc. Insider Trading Activity

Septerna, Inc. President and COO Elizabeth Bhatt exercised stock options and sold shares in a planned transaction.

Rhea-AI Filing Summary

Septerna, Inc. President and COO Elizabeth Bhatt exercised stock options and sold shares in a planned transaction. She exercised options for 4,000 shares of Common Stock at an exercise price of $6.81 per share, then sold the same 4,000 shares in open-market trades at weighted average prices between about $23.33 and $25.91. The sales were made under a pre-arranged Rule 10b5-1 sales plan adopted on October 20, 2025. Following these transactions, she directly owned 174,535 shares of Common Stock.

Insider Trade Summary 10b5-1

Exercise and Sale: 4,000 shares ($70K approx. pre-tax spread)

Exercise and Sale 5 txns

Insider Bhatt Elizabeth

Role President and COO

Sold 4,000 shs ($97K)

Approx. gross sale proceeds $97K

Approx. exercise cost $27K

Approx. pre-tax spread $70K

Type	Security	Shares	Price	Value
Exercise	Stock Option (Right to Buy)	4,000	$0.00	$0.00
Exercise	Common Stock	4,000	$6.81	$27K
Sale	Common Stock	2,573	$23.7558	$61K
Sale	Common Stock	1,101	$25.2394	$28K
Sale	Common Stock	326	$25.8623	$8K

Holdings After Transaction: Stock Option (Right to Buy) — 84,911 contracts (Direct); Common Stock — 174,209 shares (Direct)

Footnotes (5)

1. F1. This transaction was effected pursuant to a Rule 10b5-1 sales plan adopted by the Reporting Person on October 20, 2025.
2. F2. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $23.33 to $24.22. 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.
3. F3. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $24.79 to $25.75. 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.
4. F4. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $25.81 to $25.91. 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.
5. F5. 1/48th of the shares subject to such option vest and become exercisable in substantially equal monthly installments on each monthly anniversary of October 28, 2024, contingent upon the consummation of the Issuer's initial public offering, and subject to the Reporting Person's continuous service to the Issuer on each such date.

Key Figures

Options exercised: 4,000 shares Exercise price: $6.81/share Shares sold: 4,000 shares +5 more

8 metrics

Options exercised 4,000 shares Stock options exercised at $6.81 per share

Exercise price $6.81/share Conversion/exercise price for 4,000 option shares

Shares sold 4,000 shares Total Common Stock sold in open-market transactions

Sale price tranche 1 $23.7558/share Weighted average sale price for 2,573 shares

Sale price tranche 2 $25.2394/share Weighted average sale price for 1,101 shares

Sale price tranche 3 $25.8623/share Weighted average sale price for 326 shares

Shares held after 174,535 shares Common Stock directly owned after transactions

Option expiration 2034-09-22 Expiration date for the reported stock option grant

Key Terms

Rule 10b5-1 sales plan, Stock Option (Right to Buy), weighted average price, initial public offering, +1 more

5 terms

Rule 10b5-1 sales plan regulatory

"This transaction was effected pursuant to a Rule 10b5-1 sales plan adopted..."

Stock Option (Right to Buy) financial

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

weighted average price financial

"The price reported in Column 4 is a weighted average price."

Weighted average price is the average price of a security where each trade or component is counted according to its size, so bigger trades pull the average more than smaller ones. Think of it like calculating the average cost of a grocery haul where items you bought more of have greater influence on the final per-item cost. Investors use it to understand the true average price paid or received, judge execution quality, and compare trading performance against market movement.

initial public offering financial

"contingent upon the consummation 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.

Common Stock financial

"underlying_security_title: "Common Stock""

Common stock represents ownership shares in a company, giving investors a stake in its success and a say in important decisions through voting rights. It is the most common type of stock traded on markets and can provide income through dividends, as well as potential for value growth. For investors, holding common stock means sharing in the company’s profits and risks.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 04/17/2026 - 07:00 PM EDT Learn about SEC filing dates

SEC Form 4

FORM 4

UNITED 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).

X

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^*

Bhatt Elizabeth

(Last) (First) (Middle)

C/O SEPTERNA, INC.

250 EAST GRAND AVENUE

(Street)

SOUTH SAN FRANCISCO CALIFORNIA 94080

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
Septerna, Inc. [ SEPN ]

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

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
04/15/2026

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

X	Form 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)
			Code	V	Amount	(A) or (D)	Price
Common Stock	04/15/2026		M		4,000	A	$6.81	178,209	D
Common Stock	04/15/2026		S(1)		2,573	D	$23.7558(2)	175,636	D
Common Stock	04/15/2026		S(1)		1,101	D	$25.2394(3)	174,535	D
Common Stock	04/15/2026		S(1)		326	D	$25.8623(4)	174,209	D

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)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Stock Option (Right to Buy)	$6.81	04/15/2026		M			4,000	(5)	09/22/2034	Common Stock	4,000	$0	84,911	D

Explanation of Responses:

1. This transaction was effected pursuant to a Rule 10b5-1 sales plan adopted by the Reporting Person on October 20, 2025.

2. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $23.33 to $24.22. 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.

3. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $24.79 to $25.75. 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.

4. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $25.81 to $25.91. 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.

5. 1/48th of the shares subject to such option vest and become exercisable in substantially equal monthly installments on each monthly anniversary of October 28, 2024, contingent upon the consummation of the Issuer's initial public offering, and subject to the Reporting Person's continuous service to the Issuer on each such date.

	/s/ Mark A. Wilson, Attorney-in-Fact	04/17/2026
	** 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 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)