[Form 4] Lyell Immunopharma, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Form 4 snapshot – Lyell Immunopharma (LYEL): On 07/25/2025 ARCH Venture Partners IX and its affiliated funds filed a Form 4 updating their Lyell holdings after the company’s 1-for-20 reverse stock split on 05/27/2025.

• ARCH Venture Fund IX, L.P. and ARCH Venture Fund IX Overage, L.P. each report 910,317 post-split common shares, held indirectly through the venture vehicles.
• The combined 1.82 million shares leave the ARCH complex classified as a 10%+ beneficial owner under Section 16.
• No purchases, sales, or derivative transactions are listed; the filing’s primary purpose is to restate share counts and confirm insider status.
• Managing directors Keith Crandell, Robert Nelsen and Clinton Bybee disclaim personal ownership beyond their pecuniary interests.

The disclosure signals continued, substantial venture-backer support but carries neutral trading implications because no new capital movement occurred.

Positive

• ARCH funds remain a 10%+ holder, signalling continued strategic backing for LYEL.
• Transparent post-split disclosure ensures shareholders understand updated insider ownership levels.

Negative

• No new share purchases were reported, so the filing offers no incremental bullish signal.

Insights

Securities Analyst

TL;DR: Procedural update, no buy/sell signal.

This Form 4 merely adjusts ARCH’s reported Lyell share count for the recent 1-for-20 reverse split. Their aggregate 1.82 m shares still exceed 10%, underscoring long-term involvement but not reflecting fresh conviction or liquidity events. With zero transaction codes and no derivative activity, the filing is informational; share-price impact should be minimal.

Corporate Governance Expert

TL;DR: Confirms insider status post-split.

Maintaining >10% ownership obliges ARCH entities to ongoing Section 16 reporting—this filing demonstrates compliance. The layered GP/LP structure and express disclaimers limit personal liability for managers, a standard governance practice. Investors should view this as routine housekeeping rather than a strategic shift.

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).

1. Name and Address of Reporting Person^*

ARCH Venture Partners IX, LLC

(Last) (First) (Middle)

8755 W. HIGGINS ROAD, SUITE 1025

(Street)

CHICAGO IL 60631

(City) (State) (Zip)

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

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

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

3. Date of Earliest Transaction (Month/Day/Year)
07/25/2025

4. If Amendment, Date of Original Filed (Month/Day/Year)

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

	Form filed by One Reporting Person
X	Form filed by More than One Reporting Person

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								910,317(3)	I	By ARCH Venture Fund IX, L.P.(1)
Common Stock								910,317(3)	I	By ARCH Venture Fund IX Overage, L.P.(2)

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

1. Name and Address of Reporting Person^*

ARCH Venture Partners IX, LLC

(Last) (First) (Middle)

8755 W. HIGGINS ROAD, SUITE 1025

(Street)

CHICAGO IL 60631

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

ARCH Venture Partners IX, L.P.

(Last) (First) (Middle)

8755 W. HIGGINS ROAD, SUITE 1025

(Street)

CHICAGO IL 60631

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

ARCH Venture Partners IX Overage, L.P.

(Last) (First) (Middle)

8755 W. HIGGINS ROAD, SUITE 1025

(Street)

CHICAGO IL 60631

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

ARCH Venture Fund IX, L.P.

(Last) (First) (Middle)

8755 W. HIGGINS ROAD, SUITE 1025

(Street)

CHICAGO IL 60631

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

ARCH Venture Fund IX Overage, L.P.

(Last) (First) (Middle)

8755 W. HIGGINS ROAD, SUITE 1025

(Street)

CHICAGO IL 60631

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

CRANDELL KEITH

(Last) (First) (Middle)

C/O ARCH VENTURE PARTNERS IX, LLC

8755 W. HIGGINS ROAD, SUITE 1025

(Street)

CHICAGO IL 60631

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

BYBEE CLINTON

(Last) (First) (Middle)

C/O ARCH VENTURE PARTNERS IX, LLC

8755 W. HIGGINS ROAD, SUITE 1025

(Street)

CHICAGO IL 60631

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

NELSEN ROBERT

(Last) (First) (Middle)

8755 W. HIGGINS ROAD, SUITE 1025

(Street)

CHICAGO IL 60631

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

Explanation of Responses:

1. These shares are directly held by ARCH Venture Fund IX, L.P. ("ARCH IX"). ARCH Venture Partners IX, L.P. ("GPLP"), as the sole general partner of ARCH IX, may be deemed to beneficially own the shares held by ARCH IX. ARCH Venture Partners IX, LLC ("GPLLC"), as the sole general partner of GPLP, may be deemed to beneficially own the shares held by ARCH IX. As managing directors of GPLLC, each of Keith Crandell, Robert Nelsen and Clinton Bybee (the "ARCH Managing Directors"), may be deemed to beneficially own the shares held by ARCH IX. Each of GPLP, GPLLC and the ARCH Managing Directors disclaims beneficial ownership of the securities reported herein, except to the extent of their pecuniary interest therein, if any.

2. These shares are directly held by ARCH Venture Fund IX Overage, L.P. ("ARCH Overage"). ARCH Venture Partners IX Overage, L.P. ("Overage GPLP"), as the sole general partner of ARCH Overage, may be deemed to beneficially own the shares held by ARCH Overage. GPLLC, as the sole general partner of Overage GPLP, may be deemed to beneficially own the shares held by ARCH Overage. As managing directors of GPLLC, each of the ARCH Managing Directors may be deemed to beneficially own the shares held by ARCH Overage. Each of Overage GPLP, GPLLC and the ARCH Managing Directors disclaims beneficial ownership of the securities reported herein, except to the extent of their pecuniary interest therein, if any.

3. The amount of shares reported herein reflects a 1-for-20 reverse stock split that occurred on May 27, 2025.

Remarks:

Due to overlapping managing directors, a separate Form 3 was filed for the purchase of common stock of Lyell by ARCH Venture Fund XIII, L.P., and related entities: ARCH Venture Partners XIII, L.P., ARCH Venture Partners XIII, LLC, Steven Gillis, Kristina Burow and Paul Berns.

	ARCH Venture Partners IX, LLC, By: /s/ Mark McDonnell, as Attorney-in-Fact for Robert Nelsen, Managing Director	07/29/2025
	ARCH Venture Partners IX, L.P., By: ARCH Venture Partners IX, LLC, its General Partner, By: /s/ Mark McDonnell, as Attorney-in-Fact for Keith Crandell, Managing Director	07/29/2025
	ARCH Venture Partners IX Overage, L.P., By: ARCH Venture Partners IX, LLC, its General Partner, By: /s/ Mark McDonnell, as Attorney-in-Fact for Keith Crandell, Managing Director	07/29/2025
	ARCH Venture Fund IX, L.P., By: ARCH Venture Partners IX, L.P., its General Partner, By: ARCH Venture Partners IX, LLC, its General Partner, By: /s/ Mark McDonnell, as Attorney-in-Fact for Keith Crandell, Managing Director	07/29/2025
	ARCH Venture Fund IX Overage, L.P., By: ARCH Venture Partners IX Overage, L.P., its General Partner, By: ARCH Venture Partners IX, LLC, its General Partner, By: /s/ Mark McDonnell, as Attorney-in-Fact for Keith Crandell, Managing Director	07/29/2025
	Keith Crandell, Managing Director, By: /s/ Mark McDonnell, as Attorney-in-Fact	07/29/2025
	Clinton Bybee, Managing Director, By: /s/ Mark McDonnell, as Attorney-in-Fact	07/29/2025
	Robert Nelsen, Managing Director, By: /s/ Mark McDonnell, as Attorney-in-Fact	07/29/2025
	** 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).
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FAQ

How many Lyell (LYEL) shares do ARCH Venture funds hold after the reverse split?

ARCH Venture Fund IX and its Overage fund report a combined 1,820,634 common shares following the 1-for-20 split.

Why did ARCH file this Form 4 for Lyell Immunopharma?

The filing updates the insider share count to reflect the May 27 2025 1-for-20 reverse stock split and confirms 10% ownership status.

Did ARCH buy or sell any LYEL shares on 07/25/2025?

No. The Form 4 lists no acquisition or disposition codes; it is an ownership update only.

Who are the insiders associated with this ownership filing?

Managing directors Keith Crandell, Robert Nelsen, and Clinton Bybee are listed as indirect beneficial owners through ARCH entities.

Does this filing affect Lyell’s share count or valuation?

It has no direct impact on share count or valuation; it simply restates insider holdings post-split.