Baker Bros. Advisors (IDYA) reports 5.2% IDEAYA stake and capped warrants

Rhea-AI Filing Summary

IDEAYA Biosciences, Inc. has a significant institutional holder group led by Baker Bros. Advisors LP and related entities and individuals. These reporting persons disclose beneficial ownership of 5,010,030 shares of IDEAYA common stock, representing 5.2% of the class based on 96,375,637 shares outstanding as of June 30, 2026.

The shares are held through Baker Brothers Life Sciences, L.P. and 667, L.P., with Baker Bros. Advisors LP having sole voting and dispositive power under management agreements. The funds also hold prefunded warrants with a $0.0001 per-share exercise price and no expiration date. These warrants are only exercisable to the extent that, after exercise, the holders and certain affiliates would not beneficially own more than a specified Maximum Percentage, initially 4.99%, adjustable by written notice up to 19.99% effective after 61 days. Due to these limitations, the funds cannot presently exercise any of the prefunded warrants.

Key Figures

Beneficial ownership: 5,010,030 shares Ownership percentage: 5.2% Shares outstanding: 96,375,637 shares +4 more

7 metrics

Beneficial ownership 5,010,030 shares Common Stock beneficially owned by the reporting persons

Ownership percentage 5.2% Percentage of IDEAYA common stock class beneficially owned

Shares outstanding 96,375,637 shares Common Stock outstanding as of June 30, 2026

Prefunded warrant exercise price $0.0001 per share Exercise price of IDEAYA prefunded warrants held by the funds

Initial Maximum Percentage 4.99% Initial beneficial ownership cap for warrant exercises

Maximum adjustable cap 19.99% Highest ownership cap the funds may elect for warrant exercises

Waiting period for cap increase 61 days Delay after notice before an increased Maximum Percentage becomes effective

Key Terms

prefunded warrants, beneficially own, Maximum Percentage, Rule 13d-3, +1 more

5 terms

prefunded warrants financial

"the Funds directly hold prefunded warrants with no expiration date with an exercise price"

Prefunded warrants are a security that gives the holder the right to convert the warrant into a share after paying a very small remaining amount because almost the full purchase price was paid upfront. They matter to investors because exercising them increases the company’s outstanding shares (dilution) and can provide immediate cash to the issuer while allowing holders to bypass ownership limits or simplify timing, similar to buying a nearly-complete gift card that only needs a tiny top-up to use.

beneficially own regulatory

"would beneficially own in the aggregate, for purposes of Rule 13d-3"

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.

Maximum Percentage regulatory

"no more than 4.99% of the outstanding Common Stock (the "Maximum Percentage")"

Rule 13d-3 regulatory

"for purposes of Rule 13d-3 , as amended, no more than 4.99%"

Rule 13d-3 defines who is treated as the beneficial owner of a company’s shares for U.S. securities disclosure rules — essentially anyone who has the power to vote or direct how shares are voted, or the power to buy or sell them, even if they don’t hold the certificates. For investors this matters because crossing certain ownership thresholds triggers public filing and disclosure obligations and signals potential control or influence, much like having the keys to a car implies you can drive it even if it’s registered to someone else.

Section 13(d) group regulatory

"any persons who are members of a Section 13(d) group with the holders"

FAQ

What percentage of IDEAYA Biosciences (IDYA) does Baker Bros. Advisors report owning?

Baker Bros. Advisors and related reporting persons report beneficial ownership of 5.010,030 shares of IDEAYA common stock, representing 5.2% of the outstanding shares, based on 96,375,637 shares outstanding as of June 30, 2026.

How many IDEAYA (IDYA) shares does Baker Bros. Advisors have voting control over?

The reporting persons have sole voting power over 5,010,030 shares of IDEAYA common stock. They report 0 shares with shared voting power and also hold sole dispositive power over the same 5,010,030 shares.

What are the terms of the prefunded warrants held in IDEAYA (IDYA) by the Baker Bros. funds?

The funds hold prefunded warrants with a $0.0001 per-share exercise price and no expiration date. These warrants are subject to a Maximum Percentage ownership cap, limiting post-exercise beneficial ownership under Rule 13d-3.

Why can’t the Baker Bros. funds currently exercise their IDEAYA (IDYA) prefunded warrants?

The funds cannot presently exercise the $0.0001 prefunded warrants because exercise is limited by the Maximum Percentage cap, initially 4.99%, which restricts post-exercise beneficial ownership of IDEAYA common stock.

Can the Maximum Percentage ownership cap on IDEAYA (IDYA) warrants be changed by the Baker Bros. funds?

Yes. The funds may increase or decrease the Maximum Percentage up to 19.99% by written notice to IDEAYA. Any increase becomes effective on the 61st day after the issuer receives the notice.

Who are the reporting persons in the IDEAYA (IDYA) Schedule 13G filing?

The reporting persons are Baker Bros. Advisors LP, Baker Bros. Advisors (GP) LLC, and individuals Julian C. Baker and Felix J. Baker, who may be deemed to beneficially own securities held by the Baker Bros. funds.

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Available on EDGAR 08/14/2026 - 04:04 PM Accepted by SEC EDGAR 08/14/2026 - 04:01 PM Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

IDEAYA Biosciences, Inc.

(Name of Issuer)

Common Stock, par value $0.0001 per share

(Title of Class of Securities)

45166A102

(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): 45166A102

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 5,010,030.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 5,010,030.00
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

5,010,030.00

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)

5.2 %

12

Type of Reporting Person (See Instructions)

IA, PN

SCHEDULE 13G

CUSIP Number(s): 45166A102

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 5,010,030.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 5,010,030.00
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

5,010,030.00

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)

5.2 %

12

Type of Reporting Person (See Instructions)

HC, OO

SCHEDULE 13G

CUSIP Number(s): 45166A102

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 5,010,030.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 5,010,030.00
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

5,010,030.00

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)

5.2 %

12

Type of Reporting Person (See Instructions)

HC, IN

SCHEDULE 13G

CUSIP Number(s): 45166A102

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 5,010,030.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 5,010,030.00
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

5,010,030.00

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)

5.2 %

12

Type of Reporting Person (See Instructions)

HC, IN

SCHEDULE 13G

Item 1.
(a)	Name of issuer: IDEAYA Biosciences, Inc.
(b)	Address of issuer's principal executive offices: 5000 Shoreline Court, Suite 300, South San Francisco, CA 94080
Item 2.
(a)	Name of person filing: This Schedule 13G 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 $0.0001 per share
(e)	CUSIP Number(s): 45166A102
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 Schedule 13G are incorporated herein by reference. Set forth below is the aggregate number of shares of Common Stock ("Common Stock") of IDEAYA Biosciences, Inc. (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 5,010,030 shares of Common Stock directly held by the Funds. In addition, the Funds directly hold prefunded warrants with no expiration date with an exercise price of $0.0001 per share of Common Stock ("$0.0001 Prefunded Warrants"), subject to the limitations on exercise described below. Due to such limitations the Funds cannot presently exercise any of the $0.0001 Prefunded Warrants. The $0.0001 Prefunded Warrants are only exercisable to the extent that after giving effect or immediately prior to such exercise the holders thereof, their affiliates and any persons who are members of a Section 13(d) group with the holders or one of their affiliates would beneficially own in the aggregate, for purposes of Rule 13d-3 under the Securities Exchange Act of 1934, as amended, no more than 4.99% of the outstanding Common Stock (the "Maximum Percentage"). By written notice to the Issuer, the Funds may from time to time increase or decrease the Maximum Percentage applicable to that Fund to any other percentage not in excess of 19.99%. Any such increase will not be effective until the 61st day after such notice is delivered to the Issuer. As a result of these restrictions, the number of shares of Common Stock that may be issued upon exercise of the $0.0001 Prefunded Warrants by the above holders may change depending upon changes in the outstanding Common Stock. 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 Schedule 13G is incorporated herein by reference. The percentage of beneficial ownership for each of the Reporting Persons reported herein is based on 96,375,637 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 August 4, 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 5,010,030 shares of Common Stock directly held by the Funds.
	(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 5,010,030 shares of Common Stock directly held by the Funds.
	(iv) Shared power to dispose or to direct the disposition of: 0
Item 5.	Ownership of 5 Percent or Less of a Class.
	Not Applicable
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
Date:	08/14/2026

Baker Bros. Advisors (GP) LLC

Signature:	/s/ Scott L. Lessing
Name/Title:	Scott L. Lessing/ President
Date:	08/14/2026

Julian C. Baker

Signature:	/s/ Julian C. Baker
Name/Title:	Julian C. Baker
Date:	08/14/2026

Felix J. Baker

Signature:	/s/ Felix J. Baker
Name/Title:	Felix J. Baker
Date:	08/14/2026

Exhibit Information

EXHIBIT 99.1 Joint Filing Agreement