[Form 3] Lyell Immunopharma, Inc. Initial Statement of Beneficial Ownership

Rhea-AI Filing Summary

ARCH Venture Fund XIII, L.P. and affiliated entities have filed a Form 3 disclosing their initial beneficial ownership in Lyell Immunopharma (LYEL).

• Shares acquired: 938,438 common shares
• Purchase date / price: 25-Jul-2025 at $13.32 per share (per securities-purchase agreement dated 24-Jul-2025)
• Ownership status: Indirectly held through ARCH Venture Fund XIII, L.P.; the group is now classified as a 10 %+ owner under Section 16(a)
• Control structure: ARCH Venture Partners XIII, L.P. is the GP of the fund, managed by ARCH Venture Partners XIII, LLC whose investment committee members—Keith Crandell, Robert Nelsen, Kristina Burow, Paul Berns and Steven Gillis—share voting/dispositive power but disclaim beneficial ownership beyond pecuniary interest

The filing signals a sizeable insider position (≈ $12.5 million) and provides investors with updated information on Lyell’s ownership structure.

Positive

• Substantial insider purchase of 938,438 LYEL shares, indicating confidence from a sophisticated biotech investor.
• 10 %+ ownership threshold crossed, potentially aligning ARCH’s interests with minority shareholders.

Negative

• Increased ownership concentration could amplify governance influence of a single investor group.

Insights

Securities Analyst

TL;DR – Significant insider buy; signals confidence, limited near-term financial impact.

The ARCH group’s 938 k-share purchase elevates them to 10 %+ holder status, a threshold that often draws institutional attention. While the buy represents roughly one week of LYEL’s average trading volume, it does not alter fundamentals. However, venture-capital sponsorship can improve market perception, provide follow-on capital and influence strategic direction. Because the transaction was executed at market (no discount), it may be viewed positively by minority shareholders.

Portfolio Manager

TL;DR – Moderately bullish ownership change; watch for future sales windows.

An experienced life-sciences investor is now locked into a meaningful stake, enhancing governance oversight but also concentrating voting power. The purchase price of $13.32 was well above recent lows, suggesting conviction. Liquidity risk is low given the position size vs. float. I classify the disclosure as modestly positive but not immediately price-moving; monitor subsequent Form 4s for follow-on activity or partial exits.

SEC Form 3

FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

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:			3235-0104
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1. Name and Address of Reporting Person^*

ARCH Venture Fund XIII, L.P.

(Last) (First) (Middle)

8755 W. HIGGINS ROAD, SUITE 1025

(Street)

CHICAGO IL 60631

(City) (State) (Zip)

2. Date of Event Requiring Statement (Month/Day/Year)
07/25/2025

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

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

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

5. 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 Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)
Common Stock	938,438(1)	I	By: ARCH Venture Fund XIII, L.P.(2)

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

1. Name and Address of Reporting Person^*

ARCH Venture Fund XIII, 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 XIII, 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 XIII, 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^*

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^*

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)

1. Name and Address of Reporting Person^*

Burow Kristina

(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^*

GILLIS STEVEN

(Last) (First) (Middle)

C/O ARCH VENTURE PARTNERS

8755 WEST 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^*

BERNS PAUL L

(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 were purchased on July 25, 2025 pursuant to a securities purchase agreement dated July 24, 2025 at a price per share of $13.32.

2. These shares are directly held by ARCH Venture Fund XIII, L.P. ("ARCH XIII"). ARCH Venture Partners XIII, L.P. ("AVP XIII LP") is the general partner of ARCH XIII. ARCH Venture Partners XIII, LLC ("AVP XIII LLC") is the general partner of AVP XIII LP. Keith Crandell, Robert Nelsen, Kristina Burow, Paul Berns and Steven Gillis are members of the investment committee of AVP XIII LLC (the "AVP XIII LLC Committee Members"). Each of AVP XIII LP and AVP XIII LLC may be deemed to beneficially own the shares held by ARCH XIII, and each of the AVP XIII LLC Committee Members may be deemed to share the power to direct the disposition and vote of the shares held by ARCH XIII. Each of AVP XIII LP, AVP XIII LLC and the AVP XIII LLC Committee Members disclaims beneficial ownership except to the extent of their pecuniary interest therein, if any.

	ARCH Venture Partners XIII, LLC, By: /s/ Mark McDonnell, as Attorney-in-Fact for Keith Crandell, Managing Director	07/29/2025
	ARCH Venture Partners XIII, L.P., By: ARCH Venture Partners XIII, LLC, its General Partner, By: /s/ Mark McDonnell, as Attorney-in-Fact for Keith Crandell, Managing Director	07/29/2025
	ARCH Venture Fund XIII, L.P., By: ARCH Venture Partners XIII, L.P., its General Partner, By: ARCH Venture Partners XIII, 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
	Robert Nelsen, Managing Director, By: /s/ Mark McDonnell, as Attorney-in-Fact	07/29/2025
	Kristina Burow, Managing Director, By: /s/ Mark McDonnell, as Attorney-in-Fact	07/29/2025
	Steven Gillis, Managing Director, By: /s/ Mark McDonnell, as Attorney-in-Fact	07/29/2025
	Paul Berns, Managing Director, By: /s/ Mark McDonnell, as Attorney-in-Fact	07/29/2025
	** Signature of Reporting Person	Date
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FAQ

How many Lyell (LYEL) shares did ARCH Venture Fund XIII purchase?

938,438 common shares were acquired as disclosed in the Form 3.

At what price were the LYEL shares bought?

The filing states a purchase price of $13.32 per share.

Why did ARCH Venture Fund XIII file a Form 3?

Crossing the 10 % ownership threshold requires an initial beneficial-ownership statement under Section 16(a).

Who controls the newly acquired LYEL shares?

Shares are indirectly held through ARCH Venture Fund XIII, L.P., with voting/dispositive power shared by the ARCH Venture Partners XIII, LLC investment committee members.

Does the filing imply future capital support for Lyell Immunopharma?

While not guaranteed, venture-fund stakes often signal willingness to provide follow-on financing if strategic needs arise.