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Baker Bros. Advisors LP and related reporting persons filed Amendment No. 13 reporting their beneficial ownership in Cerus Corporation common stock. They beneficially own 6,395,431 shares of common stock held by Baker Brothers Life Sciences, L.P. and 667, L.P., over which the Adviser has complete investment and voting discretion. This represents 3.2% of the 201,457,000 shares outstanding as of June 30, 2026. Julian C. Baker and Felix J. Baker each also beneficially own 19,864 shares individually, so each is reported as beneficially owning 6,415,295 shares, or 3.2% of the class. The filing states ownership of 5 percent or less of the class.
Key Figures
Beneficial ownership (funds):6,395,431 sharesBeneficial ownership per principal:6,415,295 sharesIndividually held shares:19,864 shares+3 more
6 metrics
Beneficial ownership (funds)6,395,431 sharesShares of Cerus common stock beneficially owned by the Baker Bros. funds
Beneficial ownership per principal6,415,295 sharesCerus shares beneficially owned by each of Julian C. Baker and Felix J. Baker
Individually held shares19,864 sharesCerus shares individually held by each of Julian C. Baker and Felix J. Baker
Shares outstanding201,457,000 sharesCerus common stock outstanding as of June 30, 2026
Ownership percentage3.2%Percentage of Cerus common stock beneficially owned by each reporting person
Amendment number13Amendment No. 13 to Schedule 13G for Cerus Corporation
Key Terms
beneficially own, sole dispositive power, in-kind distributions, parent holding company
4 terms
beneficially ownfinancial
"The Reporting Persons beneficially own 6,395,431 shares of Common Stock directly held by the Funds."
Beneficially own means having the economic rights and risks of a security—such as the right to receive dividends, sell the shares, or profit from price changes—whether or not your name appears on the official share register. Think of it like renting a car: you use it and reap the benefits even if the title lists someone else. Investors care because beneficial ownership determines who truly controls value, must be disclosed under securities rules, and can signal potential influence or trading activity that affects a stock’s price.
sole dispositive powerfinancial
"The Reporting Persons have sole power to dispose or direct the disposition of 6,395,431 shares of Common Stock."
Sole dispositive power is the exclusive legal authority to decide what happens to a security — for example, whether to sell, transfer, or retain shares — without needing anyone else’s permission. Investors care because it signals who truly controls the economic outcome of an investment: like holding the only key to a safe, the holder can realize gains or losses and may trigger regulatory reporting, insider rules, or influence over corporate ownership.
in-kind distributionsfinancial
"Julian C. Baker and Felix J. Baker each hold and beneficially own 19,864 shares ... received from in-kind distributions."
parent holding companyfinancial
"If a parent holding company has filed this schedule, pursuant to (ii)(G), so indicate under Item 3(g)."
FAQ
AI-generated questions and answers. How Rhea-AI works. Not financial advice.
What percentage of Cerus Corporation (CERS) does Baker Bros. report owning?
Baker Bros. Advisors and related reporting persons report beneficial ownership of 3.2% of Cerus common stock. This percentage is based on 201,457,000 shares outstanding as of June 30, 2026, as disclosed in Cerus’s Form 10-Q.
How many Cerus (CERS) shares are beneficially owned by the Baker Bros. funds and principals?
The Baker Bros. funds beneficially own 6,395,431 shares of Cerus common stock. Julian C. Baker and Felix J. Baker each beneficially own 6,415,295 shares, including 19,864 shares individually received from in-kind distributions.
What is the total Cerus (CERS) share count used to calculate Baker Bros.’ ownership?
The ownership percentages are calculated using 201,457,000 shares of Cerus common stock outstanding. This share count is as of June 30, 2026 and comes from Cerus Corporation’s Form 10-Q filed on July 30, 2026.
Who has voting and investment power over the Cerus (CERS) shares held by Baker Bros. funds?
Baker Bros. Advisors LP has sole power to vote and dispose of 6,395,431 shares held by the funds. Management agreements give the Adviser complete and unlimited discretion over investments and voting power for securities held by the funds.
Do the Baker Bros. reporting persons share voting or dispositive power over Cerus (CERS) shares?
The reporting persons disclose sole voting and dispositive power over the reported Cerus shares and 0 shared voting or dispositive power. Each of Julian and Felix Baker also has sole power over 19,864 individually held shares.
What does “ownership of 5 percent or less” mean for Baker Bros. in Cerus (CERS)?
The Schedule 13G/A indicates “Ownership of 5 percent or less of a class,” meaning the reporting persons’ aggregate holdings are below the 5% threshold. Their reported 3.2% stake reflects this reduced ownership level in Cerus common stock.
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
SCHEDULE 13G
UNDER THE SECURITIES EXCHANGE ACT OF 1934
(Amendment No. 13)
Cerus Corporation
(Name of Issuer)
Common Stock, par value $0.001 per share
(Title of Class of Securities)
157085101
(CUSIP Number)
06/30/2026
(Date of Event Which Requires Filing of this Statement)
Check the appropriate box to designate the rule pursuant to which this Schedule is filed:
Rule 13d-1(b)
Rule 13d-1(c)
Rule 13d-1(d)
schemaVersion:
SCHEDULE 13G
CUSIP Number(s):
157085101
1
Names of Reporting Persons
Baker Bros. Advisors LP
2
Check the appropriate box if a member of a Group (see instructions)
(a)
(b)
3
Sec Use Only
4
Citizenship or Place of Organization
DELAWARE
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
6,395,431.00
6
Shared Voting Power
0.00
7
Sole Dispositive Power
6,395,431.00
8
Shared Dispositive Power
0.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
6,395,431.00
10
Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)
11
Percent of class represented by amount in row (9)
3.2 %
12
Type of Reporting Person (See Instructions)
IA, PN
SCHEDULE 13G
CUSIP Number(s):
157085101
1
Names of Reporting Persons
Baker Bros. Advisors (GP) LLC
2
Check the appropriate box if a member of a Group (see instructions)
(a)
(b)
3
Sec Use Only
4
Citizenship or Place of Organization
DELAWARE
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
6,395,431.00
6
Shared Voting Power
0.00
7
Sole Dispositive Power
6,395,431.00
8
Shared Dispositive Power
0.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
6,395,431.00
10
Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)
11
Percent of class represented by amount in row (9)
3.2 %
12
Type of Reporting Person (See Instructions)
HC, OO
SCHEDULE 13G
CUSIP Number(s):
157085101
1
Names of Reporting Persons
Julian C. Baker
2
Check the appropriate box if a member of a Group (see instructions)
(a)
(b)
3
Sec Use Only
4
Citizenship or Place of Organization
UNITED STATES
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
6,415,295.00
6
Shared Voting Power
0.00
7
Sole Dispositive Power
6,415,295.00
8
Shared Dispositive Power
0.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
6,415,295.00
10
Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)
11
Percent of class represented by amount in row (9)
3.2 %
12
Type of Reporting Person (See Instructions)
HC, IN
SCHEDULE 13G
CUSIP Number(s):
157085101
1
Names of Reporting Persons
Felix J. Baker
2
Check the appropriate box if a member of a Group (see instructions)
(a)
(b)
3
Sec Use Only
4
Citizenship or Place of Organization
UNITED STATES
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
6,415,295.00
6
Shared Voting Power
0.00
7
Sole Dispositive Power
6,415,295.00
8
Shared Dispositive Power
0.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
6,415,295.00
10
Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)
11
Percent of class represented by amount in row (9)
3.2 %
12
Type of Reporting Person (See Instructions)
HC, IN
SCHEDULE 13G
Item 1.
(a)
Name of issuer:
Cerus Corporation
(b)
Address of issuer's principal executive offices:
1220 Concord Ave, Suite 600, Concord, CA 94520
Item 2.
(a)
Name of person filing:
This Amendment No. 13 is being filed by Baker Bros. Advisors LP (the "Adviser"), Baker Bros. Advisors (GP) LLC (the "Adviser GP"), Julian C. Baker and Felix J. Baker (collectively, the "Reporting Persons").
(b)
Address or principal business office or, if none, residence:
The business address of each of the Reporting Persons is:
c/o Baker Bros. Advisors LP
860 Washington Street, 3rd Floor
New York, NY 10014
(212) 339-5690
(c)
Citizenship:
The Adviser is a limited partnership organized under the laws of the State of Delaware. The Adviser GP is a limited liability company organized under the laws of the State of Delaware. The citizenship of each of Julian C. Baker and Felix J. Baker is the United States of America.
(d)
Title of class of securities:
Common Stock, par value $0.001 per share
(e)
CUSIP No.:
157085101
Item 3.
If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)
Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)
Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)
Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)
Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)
An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)
An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)
A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)
A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)
A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)
A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J),
please specify the type of institution:
(k)
Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.
Ownership
(a)
Amount beneficially owned:
Items 5 through 9 of each of the cover pages to this Amendment No. 13 are incorporated herein by reference. Set forth below is the aggregate number of shares of Common Stock ("Common Stock") of Cerus Corporation (the "Issuer") directly held in the aggregate by Baker Brothers Life Sciences, L.P. ("Life Sciences") and 667, L.P. ("667", and together with Life Sciences, the "Funds") which may be deemed to be indirectly beneficially owned by the Reporting Persons.
The Reporting Persons beneficially own 6,395,431 shares of Common Stock directly held by the Funds. Additionally, Julian C. Baker and Felix J. Baker each hold and beneficially own 19,864 shares of Common Stock of the Issuer previously received from in-kind distributions.
Pursuant to the management agreements, as amended, among the Adviser, the Funds and their respective general partners, the Funds' respective general partners relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds, and thus the Adviser has complete and unlimited discretion and authority with respect to the Funds' investments and voting power over investments.
The Adviser GP is the sole general partner of the Adviser. The Adviser GP, Felix J. Baker and Julian C. Baker as managing members of the Adviser GP, and the Adviser may be deemed to be beneficial owners of securities of the Issuer directly held by the Funds.
(b)
Percent of class:
The information in Item 11 of each of the cover pages to this Amendment No. 13 is incorporated herein by reference. The percentage of beneficial ownership for each of the Reporting Persons reported herein is based on 201,457,000 shares of Common Stock outstanding as of June 30, 2026, as reported in the Issuer's Form 10-Q filed with the Securities and Exchange Commission on July 30, 2026.
(c)
Number of shares as to which the person has:
(i) Sole power to vote or to direct the vote:
The Reporting Persons have sole power to vote or direct the vote of 6,395,431 shares of Common Stock directly held by the Funds. In addition, Julian C. Baker and Felix J. Baker each have the sole power to vote or direct the vote of 19,864 shares of Common Stock individually held and beneficially owned by them.
(ii) Shared power to vote or to direct the vote:
0
(iii) Sole power to dispose or to direct the disposition of:
The Reporting Persons have sole power to dispose or direct the disposition of 6,395,431 shares of Common Stock directly held by the Funds. In addition, Julian C. Baker and Felix J. Baker each have the sole power to dispose or direct the disposition of 19,864 shares of Common Stock individually held and beneficially owned by them.
(iv) Shared power to dispose or to direct the disposition of:
0
Item 5.
Ownership of 5 Percent or Less of a Class.
Ownership of 5 percent or less of a class
Item 6.
Ownership of more than 5 Percent on Behalf of Another Person.
Not Applicable
Item 7.
Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
If a parent holding company has filed this schedule, pursuant to Rule 13d-1(b)(ii)(G), so indicate under Item 3(g) and attach an exhibit stating the identity and the Item 3 classification of the relevant subsidiary. If a parent holding company has filed this schedule pursuant to Rule 13d-1(c) or Rule 13d-1(d), attach an exhibit stating the identification of the relevant subsidiary.
The information in Item 4 is incorporated herein by reference.
Item 8.
Identification and Classification of Members of the Group.
Not Applicable
Item 9.
Notice of Dissolution of Group.
Not Applicable
Item 10.
Certifications:
By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under § 240.14a-11.
SIGNATURE
After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.
Baker Bros. Advisors LP
Signature:
/s/ Scott L. Lessing
Name/Title:
Scott L. Lessing/ President By: Baker Bros. Advisors (GP) LLC, its general partner
