Lyell Immunopharma (LYEL) CEO sells shares for taxes, keeps 63,899

Rhea-AI Filing Summary

Lyell Immunopharma, Inc. (LYEL) reported that its President and CEO, Lynn Seely, had an automatic sale of 9,589 shares of common stock on 2026-08-21 at $15.54 per share. The shares were sold to cover a tax withholding obligation from vested restricted stock units, leaving 63,899 shares held directly.

Insider Trade Summary

Net Seller: 9,589 shares

Net Sell 1 txn

Insider Seely Lynn

Role President and CEO

Sold 9,589 shs ($149K)

Type	Security	Shares	Price	Value
Sale	Common Stock F1	9,589	$15.54	$149K

Holdings After Transaction: Common Stock — 63,899 shares (Direct)

Footnotes (1)

1. F1. Shares automatically sold to cover tax withholding obligation from settlement of vested restricted stock units.

Key Figures

Shares sold: 9,589 shares of Common Stock Sale price per share: $15.54 per share Shares held after transaction: 63,899 shares of Common Stock

3 metrics

Shares sold 9,589 shares of Common Stock Automatic sale on 2026-08-21 to cover tax withholding

Sale price per share $15.54 per share Price for the 9,589 LYEL shares sold on 2026-08-21

Shares held after transaction 63,899 shares of Common Stock Direct holdings of Lynn Seely following the sale

Key Terms

restricted stock units, tax withholding obligation, Form 4

3 terms

restricted stock units financial

"from settlement of vested restricted stock units."

Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.

tax withholding obligation financial

"sold to cover tax withholding obligation from settlement"

Form 4 regulatory

"as disclosed in the Form 4 filing."

Form 4 is a official document that company insiders, such as executives or major shareholders, file with regulators whenever they buy or sell company shares. It provides transparency about how those with inside knowledge are trading, helping investors see if insiders are confident in the company's prospects or may be selling for personal reasons. This information can influence investor decisions by revealing insiders' perspectives on the company's value.

FAQ

What insider transaction did LYEL report for CEO Lynn Seely?

Lyell Immunopharma (LYEL) reported that CEO Lynn Seely sold 9,589 shares of common stock on 2026-08-21 at $15.54 per share in an automatic sale to satisfy tax withholding from vested restricted stock units.

How many LYEL shares did CEO Lynn Seely retain after the reported sale?

After the sale, CEO Lynn Seely held 63,899 shares of Lyell Immunopharma common stock directly, as disclosed in the Form 4 filing.

Why were Lynn Seely’s LYEL shares sold in this Form 4 transaction?

The filing states the shares were automatically sold to cover a tax withholding obligation arising from the settlement of vested restricted stock units, rather than as a discretionary sale for investment purposes.

Was the LYEL insider sale under a Rule 10b5-1 trading plan?

No. The filing’s Rule 10b5-1 checkbox is not marked as an affirming plan, and the footnote describes the transaction as an automatic sale to cover tax withholding, not as a trade under a pre-arranged trading plan.

What was the price per share in Lynn Seely’s LYEL stock sale?

The reported price for the transaction was $15.54 per share for the 9,589 shares of Lyell Immunopharma common stock sold on 2026-08-21.

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

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Form 4 Insider Transactions: What Each Field Means →

Available on EDGAR 08/25/2026 - 04:07 PM Accepted by SEC EDGAR 08/25/2026 - 04:06 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).

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^*

Seely Lynn

(Last) (First) (Middle)

C/O LYELL IMMUNOPHARMA, INC.

201 HASKINS WAY

(Street)

SOUTH SAN FRANCISCO CALIFORNIA 94080

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
Lyell Immunopharma, Inc. [ LYEL ]

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

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
08/21/2026

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	08/21/2026		S		9,589(1)	D	$15.54	63,899	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

Explanation of Responses:

1. Shares automatically sold to cover tax withholding obligation from settlement of vested restricted stock units.

	/s/ Mark Meltz, Attorney-in-Fact	08/25/2026
	** 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)