Septerna SVP exercises options, sells 3,333 shares

Septerna SVP Daniel D. Long exercised 3,333 options and sold 3,333 shares under a pre‑planned Rule 10b5-1 trading plan.

Rhea-AI Filing Summary

Septerna, Inc. insider Daniel D. Long, who serves as SVP, Drug Discovery, reported an option exercise and same‑day sale of common stock. On September 1, 2026, he exercised options to acquire 3,333 shares of common stock at an exercise price of $2.76 per share and sold 3,333 shares of common stock at a weighted average price of $37.8271 per share in multiple trades between $37.34 and $38.21.

The sale was effected pursuant to a Rule 10b5-1 sales plan adopted on March 20, 2026, indicating the transactions were pre‑planned. Following the option exercise, Long held 9,085 options on Septerna common stock with a $2.76 exercise price, expiring on March 19, 2034, which vest in substantially equal monthly installments from March 1, 2024, subject to his continued service.

Insider Trade Summary 10b5-1

Exercise and Sale: 3,333 shares ($117K approx. pre-tax spread)

Exercise and Sale 3 txns

Insider Long Daniel D.

Role SVP, Drug Discovery

Sold 3,333 shs ($126K)

Approx. gross sale proceeds $126K

Approx. exercise cost $9K

Approx. pre-tax spread $117K

Type	Security	Shares	Price	Value
Exercise	Stock Option (Right to Buy) F3	3,333	$0.00	$0.00
Exercise	Common Stock	3,333	$2.76	$9K
Sale	Common Stock F1, F2	3,333	$37.8271	$126K

Holdings After Transaction: Stock Option (Right to Buy) — 9,085 contracts (Direct); Common Stock — 96,412 shares (Direct)

Footnotes (3)

1. F1. This transaction was effected pursuant to a Rule 10b5-1 sales plan adopted by the Reporting Person on March 20, 2026.
2. F2. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $37.34 to $38.21. 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. 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.

Key Figures

Shares sold: 3,333 shares Weighted average sale price: $37.8271 per share Sale price range: $37.34 to $38.21 per share +5 more

8 metrics

Shares sold 3,333 shares Common stock sold on September 1, 2026

Weighted average sale price $37.8271 per share Common stock sales on September 1, 2026, in a price range

Sale price range $37.34 to $38.21 per share Prices for multiple transactions on September 1, 2026

Options exercised 3,333 options Options exercised into common stock on September 1, 2026

Option exercise price $2.76 per share Exercise price for options converting into Septerna common stock

Remaining options held 9,085 options Options remaining after the reported exercise, expiring March 19, 2034

Option expiration date March 19, 2034 Expiration for the remaining options with a $2.76 exercise price

Rule 10b5-1 plan adoption date March 20, 2026 Date the pre‑planned sales arrangement was adopted

Key Terms

Rule 10b5-1 sales plan, weighted average price, monthly installments, vest

4 terms

Rule 10b5-1 sales plan regulatory

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

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.

monthly installments financial

"shall vest and become exercisable in substantially equal monthly installments"

Monthly installments are regular, fixed payments made each month to gradually pay off a larger amount, such as a loan or purchase. Think of it like paying for a big item in small, manageable parts instead of all at once. For investors, understanding installment payments helps gauge how debts are structured and how they might affect financial stability or cash flow over time.

vest financial

"1/48th of the shares subject to such option shall vest and become exercisable"

A vest is the process by which an employee earns the right to receive certain benefits or ownership interests, such as stock or retirement funds, over time. It’s similar to earning a reward gradually, ensuring that the benefit becomes fully yours only after a set period or meeting specific conditions. This makes it important for investors because it determines when they can actually claim or use those benefits.

FAQ

What did Septerna (SEPN) executive Daniel D. Long report in this Form 4?

He reported exercising options for 3,333 shares of Septerna common stock at $2.76 per share on September 1, 2026 and selling 3,333 shares of common stock the same day at a weighted average price of $37.8271 per share.

At what prices were the Septerna (SEPN) shares sold by Daniel D. Long?

The 3,333 shares of Septerna common stock were sold at a weighted average price of $37.8271 per share in multiple transactions at prices ranging from $37.34 to $38.21 on September 1, 2026.

Were the Septerna (SEPN) stock sales made under a Rule 10b5-1 plan?

Yes. The sale of 3,333 shares of Septerna common stock on September 1, 2026 was effected pursuant to a Rule 10b5-1 sales plan adopted by Daniel D. Long on March 20, 2026.

How many Septerna (SEPN) options does Daniel D. Long hold after this transaction?

After exercising options for 3,333 shares, Daniel D. Long held 9,085 options for Septerna common stock with an exercise price of $2.76 per share, expiring on March 19, 2034.

What is the vesting schedule for Daniel D. Long’s Septerna (SEPN) stock options?

For the option involved in this transaction, 1/48 of the shares vest and become exercisable in substantially equal monthly installments on each monthly anniversary of March 1, 2024, subject to Daniel D. Long’s continuous service to Septerna on each vesting date.

What role does Daniel D. Long hold at Septerna (SEPN)?

Daniel D. Long is an officer of Septerna, serving as SVP, Drug Discovery, and filed this Form 4 in that capacity in connection with the reported option exercise and stock sale on September 1, 2026.

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

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Available on EDGAR 09/03/2026 - 07:03 PM Accepted by SEC EDGAR 09/03/2026 - 07:01 PM 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^*

Long Daniel D.

(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)
	SVP, Drug Discovery

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
09/01/2026

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	09/01/2026		M		3,333	A	$2.76	99,745	D
Common Stock	09/01/2026		S(1)		3,333	D	$37.8271(2)	96,412	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)	$2.76	09/01/2026		M			3,333	(3)	03/19/2034	Common Stock	3,333	$0	9,085	D

Explanation of Responses:

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

2. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $37.34 to $38.21. 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. 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.

	/s/ Mark A. Wilson, Attorney-in-Fact	09/03/2026
	** 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)