Lyell Immunopharma (LYEL) CEO’s 388-share tax-related stock sale detailed in Form 4

Rhea-AI Filing Summary

Lyell Immunopharma, Inc. President and CEO Lynn Seely reported a small stock transaction related to taxes on equity compensation. On May 11, 2026, 388 shares of common stock were sold at a weighted average price of $18.91 per share to cover a tax withholding obligation from the settlement of vested restricted stock units. After this tax-related sale, Seely directly holds 73,878 shares of Lyell Immunopharma common stock, indicating that the transaction affects only a very small portion of her overall holdings and reflects a routine administrative disposition rather than a discretionary portfolio change.

Insider Trade Summary

Net Seller: 388 shares ($7,337)

Net Sell 1 txn

Insider Seely Lynn

Role President and CEO

Sold 388 shs ($7K)

Type	Security	Shares	Price	Value
Sale	Common Stock	388	$18.91	$7K

Holdings After Transaction: Common Stock — 73,878 shares (Direct, null)

Footnotes (1)

1. Shares automatically sold to cover tax withholding obligation from settlement of vested restricted stock units. The price reported above reflects the weighted average price of the shares sold. The sale price ranged from $18.91 to $19.15 per share. Upon request from the SEC staff, the Issuer, or a security holder of the Issuer, the Reporting Person will provide full information regarding the number of shares sold at each separate price within the range set forth in this Form 4.

Key Figures

Shares sold: 388 shares Average sale price: $18.91 per share Sale price range: $18.91 to $19.15 per share +1 more

4 metrics

Shares sold 388 shares Common stock sold on May 11, 2026

Average sale price $18.91 per share Weighted average sale price

Sale price range $18.91 to $19.15 per share Price range for shares sold

Post-transaction holdings 73,878 shares Directly owned after transaction

Key Terms

restricted stock units, weighted average price, open-market sale, tax withholding obligation

4 terms

restricted stock units financial

"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.

weighted average price financial

"The price reported above reflects the weighted average price of the shares sold"

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.

open-market sale financial

"transaction_action: open-market sale"

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.

tax withholding obligation financial

"Shares automatically sold to cover tax withholding obligation from settlement"

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Form 4 Insider Transactions: What Each Field Means →

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)
05/11/2026

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	05/11/2026		S		388(1)	D	$18.91(2)	73,878	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. The price reported above reflects the weighted average price of the shares sold. The sale price ranged from $18.91 to $19.15 per share. Upon request from the SEC staff, the Issuer, or a security holder of the Issuer, the Reporting Person will provide full information regarding the number of shares sold at each separate price within the range set forth in this Form 4.

	/s/ Mark Meltz, Attorney-in-Fact	06/15/2026
	** 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)

FAQ

What did Lyell Immunopharma (LYEL) CEO Lynn Seely report in this Form 4?

Lynn Seely reported selling 388 shares of Lyell Immunopharma common stock. The sale was made to cover tax withholding from vested restricted stock units, reflecting a routine administrative transaction tied to equity compensation rather than a discretionary change in investment position.

How many Lyell Immunopharma (LYEL) shares did the CEO sell and at what price?

The CEO sold 388 shares of Lyell Immunopharma common stock at a weighted average price of $18.91 per share. The sale price ranged from $18.91 to $19.15 per share, according to the disclosure accompanying this Form 4 filing.

Why were Lyell Immunopharma (LYEL) shares sold in this insider transaction?

The shares were automatically sold to satisfy a tax withholding obligation from the settlement of vested restricted stock units. This type of transaction is common with equity compensation and typically reflects tax administration rather than an active investment decision by the insider.

How many Lyell Immunopharma (LYEL) shares does the CEO hold after this transaction?

Following the tax-related sale, the CEO directly holds 73,878 shares of Lyell Immunopharma common stock. This indicates that the 388 shares sold represent a very small proportion of her overall direct ownership position in the company.

Was this Lyell Immunopharma (LYEL) insider sale a market trade or tax withholding?

While coded as a sale, the footnotes clarify the shares were sold to cover tax withholding from vested restricted stock units. That means the transaction is primarily a tax-related administrative event rather than a discretionary open-market sale decision by the CEO.