Lyell CMO’s small tax-related share sale disclosed

Lyell Immunopharma Chief Medical Officer David Shook reported a small share sale primarily to cover taxes.

Rhea-AI Filing Summary

Lyell Immunopharma Chief Medical Officer David Shook reported a small share sale primarily to cover taxes. On this Form 4, he sold 1,977 shares of common stock at $12.64 per share, with the shares automatically sold to satisfy tax withholding obligations from vested restricted stock units.

After this transaction, Shook directly owns 20,923 common shares, which includes 1,000 shares acquired on May 18, 2026 under Lyell’s 2021 Employee Stock Purchase Plan. The filing reflects a routine, tax-related disposition rather than a large discretionary sale.

Insider Trade Summary

Net Seller: 1,977 shares

Net Sell 1 txn

Insider Shook David

Role Chief Medical Officer

Sold 1,977 shs ($25K)

Type	Security	Shares	Price	Value
Sale	Common Stock	1,977	$12.64	$25K

Holdings After Transaction: Common Stock — 20,923 shares (Direct)

Footnotes (2)

1. F1. Shares automatically sold to cover tax withholding obligation from settlement of vested restricted stock units.
2. F2. Includes 1,000 shares acquired on May 18, 2026 under the Issuer's 2021 Employee Stock Purchase Plan.

Key Figures

Shares sold: 1,977 shares Sale price per share: $12.64 per share Shares held after transaction: 20,923 shares +1 more

4 metrics

Shares sold 1,977 shares Common stock sale on June 10, 2026

Sale price per share $12.64 per share Price for 1,977 common shares sold

Shares held after transaction 20,923 shares Direct common stock holdings following sale

ESPP shares acquired 1,000 shares Acquired on May 18, 2026 under 2021 Employee Stock Purchase Plan

Key Terms

restricted stock units, Employee Stock Purchase Plan, tax withholding obligation, open-market sale

4 terms

restricted stock units financial

"Shares automatically sold to cover tax withholding obligation 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.

Employee Stock Purchase Plan financial

"Includes 1,000 shares acquired on May 18, 2026 under the Issuer's 2021 Employee Stock Purchase Plan."

An employee stock purchase plan is a company program that lets workers buy shares through small payroll deductions, often at a discount to the market price and after a set offering period. Think of it like a workplace savings plan that turns into ownership: it encourages employees to share in the company’s success and can create predictable buying or selling of stock that investors watch because it affects supply, demand and employee incentives.

tax withholding obligation financial

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

open-market sale financial

"transaction_action: open-market sale, code S with tax-related footnote clarification."

An open-market sale is when a shareholder sells existing shares directly on a public exchange to any willing buyer, rather than through a private deal. Think of it like putting goods on a busy market stall where price is set by supply and demand; for investors it matters because such sales increase available supply, can put short-term downward pressure on the stock price, and signal changes in liquidity or investor confidence.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What insider transaction did Lyell Immunopharma (LYEL) report for David Shook?

Lyell Immunopharma reported that Chief Medical Officer David Shook sold 1,977 shares of common stock. The shares were automatically sold to cover tax withholding obligations arising from the settlement of vested restricted stock units, according to the Form 4 filing footnotes.

At what price did David Shook’s Lyell Immunopharma (LYEL) shares sell?

The 1,977 Lyell Immunopharma common shares sold for $12.64 per share. This price reflects the execution value for the tax-related sale tied to the settlement of vested restricted stock units reported in the Form 4 filing.

How many Lyell Immunopharma (LYEL) shares does David Shook hold after the transaction?

After the reported transaction, David Shook holds 20,923 shares of Lyell Immunopharma common stock directly. This post-transaction balance includes shares previously held as well as 1,000 shares acquired through the company’s 2021 Employee Stock Purchase Plan.

Was David Shook’s Lyell Immunopharma (LYEL) share sale discretionary or tax-related?

The sale was tax-related rather than purely discretionary. Footnotes explain that the 1,977 shares were automatically sold to cover tax withholding obligations triggered by the settlement of vested restricted stock units, a common mechanism for handling equity compensation taxes.

What role does David Shook hold at Lyell Immunopharma (LYEL)?

David Shook serves as Chief Medical Officer at Lyell Immunopharma. As an executive officer, his equity transactions in company stock are reported on Form 4, providing transparency into changes in his direct holdings of Lyell’s common shares.

Did David Shook recently acquire additional Lyell Immunopharma (LYEL) shares?

Yes. Footnotes indicate that his holdings include 1,000 shares acquired on May 18, 2026 under Lyell Immunopharma’s 2021 Employee Stock Purchase Plan, reflecting participation in the company’s employee stock ownership program.

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

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Accepted by SEC EDGAR 06/11/2026 - 04:07 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).

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^*

Shook David

(Last) (First) (Middle)

C/O LYELL IMMUNOPHARMA, INC.

201 HASKINS WAY, SUITE 101

(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)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Chief Medical Officer

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
06/10/2026

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	06/10/2026		S		1,977(1)	D	$12.64	20,923(2)	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.

2. Includes 1,000 shares acquired on May 18, 2026 under the Issuer's 2021 Employee Stock Purchase Plan.

	/s/ Mark Meltz, Attorney-in-Fact	06/11/2026
	** 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)