Ideaya Biosciences, Inc. — Janus Henderson Group plc reports beneficial ownership of 7,265,253 shares of Ideaya common stock, representing 8.3% of the class as reported on 03/31/2026. The holdings are exercised through multiple Asset Managers with shared voting and shared dispositive power over these shares on behalf of managed client accounts; the filing notes the Asset Managers disclaim rights to receive dividends or sale proceeds associated with that ownership interest.
Positive
None.
Negative
None.
Insights
Large passive position reported via multiple asset managers.
Janus Henderson's 7,265,253-share position equals 8.3% of Ideaya and is held across several SEC-registered advisers and affiliates. The filing attributes shared voting and dispositive power to the group of Asset Managers acting for client accounts.
Impact depends on trading or voting decisions by those managed portfolios; subsequent filings would show any changes in direction or concentration.
Filing clarifies attribution and disclaimer language for client holdings.
The Schedule 13G/A explains that the Asset Managers exercise investment discretion for Managed Portfolios and disclaim rights to dividends/proceeds tied to those holdings. Item 6 notes no single Managed Portfolio owns more than 5% of Ideaya.
Watch for Exhibit references identifying specific subsidiaries or advisers in future amendments.
Key Figures
Shares beneficially owned:7,265,253 sharesPercent of class:8.3%Sole voting/dispositive power:0 shares
3 metrics
Shares beneficially owned7,265,253 sharesBeneficial ownership reported as of <date>03/31/2026</date>
Percent of class<percent>8.3%</percent>Aggregate percentage of common stock beneficially owned
Sole voting/dispositive power0 sharesNo sole voting or sole dispositive power asserted in the filing
"may be deemed to be the beneficial owner of 7,265,253 common stock"
Beneficial ownership means the person or entity that actually enjoys the benefits of owning shares or other assets — such as receiving dividends, voting rights, or price gains — even if the legal title is held in another name. For investors it matters because knowing who truly controls and profits from a company reveals who can influence decisions, exposes potential conflicts of interest or hidden concentration of power, and affects transparency and risk in the stock.
Shared dispositive powerregulatory
"Shared Dispositive Power 7,265,253.00"
Managed Portfoliosfinancial
"clients which include investment companies... (collectively referred to herein as Managed Portfolios)"
Schedule 13G/Aregulatory
"Item 1. | (a) | Name of issuer: IDEAYA BIOSCIENCES, INC."
A Schedule 13G/A is an amended public filing with the U.S. securities regulator that updates a previous Schedule 13G, disclosing when an individual or group holds a substantial (typically over 5%) stake in a company and is claiming a passive, non‑controlling intent. Investors monitor these updates because rising or falling holdings can signal changing confidence, potential future moves, or shifts in voting power — like watching a public ledger where large shareholders quietly adjust their positions.
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SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
SCHEDULE 13G
UNDER THE SECURITIES EXCHANGE ACT OF 1934
(Amendment No. 6)
IDEAYA BIOSCIENCES, INC.
(Name of Issuer)
Common Stock
(Title of Class of Securities)
45166A102
(CUSIP Number)
03/31/2026
(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
JANUS HENDERSON GROUP PLC
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
JERSEY
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
0.00
6
Shared Voting Power
7,265,253.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
7,265,253.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
7,265,253.00
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)
8.3 %
12
Type of Reporting Person (See Instructions)
HC
SCHEDULE 13G
Item 1.
(a)
Name of issuer:
IDEAYA BIOSCIENCES, INC.
(b)
Address of issuer's principal executive offices:
5000 SHORELINE CT, SUITE 300
SOUTH SAN FRANCISCO, CA 94080
Item 2.
(a)
Name of person filing:
Janus Henderson Group plc
(b)
Address or principal business office or, if none, residence:
201 Bishopsgate
EC2M 3AE, United Kingdom
(c)
Citizenship:
Y9
(d)
Title of class of securities:
Common Stock
(e)
CUSIP No.:
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:
Janus Henderson Group plc (JHG) is the ultimate parent of a number of SEC-registered investment advisers and foreign equivalents thereof, including but not limited to Janus Henderson Investors US LLC, Janus Henderson Investors UK Limited, Janus Henderson Investors Australia Institutional Funds Management Limited, Janus Henderson Investors Middle East Limited, Janus Henderson Investors (Jersey) Limited, Janus Henderson Investors (Japan) Limited, Janus Henderson Investors (Singapore) Limited, Kapstream Capital Pty Limited, Privacore Capital Advisors LLC, Tabula Investment Management Limited, and Victory Park Capital Advisors LLC (each, an Asset Manager and together, the Asset Managers). The Asset Managers generally exercise investment and/or voting discretion on behalf of their clients which include investment companies, other investment advisers, institutional separate accounts and retail separate accounts (collectively referred to herein as Managed Portfolios).
As a result of their exercise of investment and/or voting discretion on behalf of the Managed Portfolios, the Asset Managers may be deemed to be the beneficial owner of 7,265,253 common stock of Ideaya Biosciences, Inc. However, the Asset Managers do not have the right to receive any dividends from, or the proceeds from the sale of, the securities held in the Managed Portfolios and disclaim any ownership associated with such rights.
(b)
Percent of class:
8.3 %
(c)
Number of shares as to which the person has:
(i) Sole power to vote or to direct the vote:
0
(ii) Shared power to vote or to direct the vote:
7265253
(iii) Sole power to dispose or to direct the disposition of:
0
(iv) Shared power to dispose or to direct the disposition of:
7265253
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.
If any other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, such securities, a statement to that effect should be included in response to this item and, if such interest relates to more than 5 percent of the class, such person should be identified. A listing of the shareholders of an investment company registered under the Investment Company Act of 1940 or the beneficiaries of employee benefit plan, pension fund or endowment fund is not required.
The Managed Portfolios have the right to receive all dividends from, and the proceeds from the sale of, the securities held in their respective accounts.
Of the Managed Portfolios, none own more than five percent of the common stock of Ideaya Biosciences, Inc.
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.
Please refer to Exhibit 99.
Item 8.
Identification and Classification of Members of the Group.
If a group has filed this schedule pursuant to §240.13d-1(b)(1)(ii)(J), so indicate under Item 3(j) and attach an exhibit stating the identity and Item 3 classification of each member of the group. If a group has filed this schedule pursuant to §240.13d-1(c) or §240.13d-1(d), attach an exhibit stating the identity of each member of the group.
N/A
Item 9.
Notice of Dissolution of Group.
Notice of dissolution of a group may be furnished as an exhibit stating the date of the dissolution and that all further filings with respect to transactions in the security reported on will be filed, if required, by members of the group, in their individual capacity. See Item 5.
N/A
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.
What stake does Janus Henderson report in IDEAYA (IDYA)?
Janus Henderson reports beneficial ownership of 7,265,253 shares, equal to 8.3% of the common stock as of 03/31/2026. The position is held via multiple asset managers acting for managed client portfolios.
Does Janus Henderson have sole voting or dispositive power over these IDYA shares?
No. The filing states 0 shares with sole voting or dispositive power and 7,265,253 shares with shared voting and shared dispositive power, indicating control is exercised jointly through the Asset Managers on behalf of clients.
Are the Janus-managed portfolios entitled to dividends or sale proceeds from these IDYA shares?
The Managed Portfolios have the right to receive dividends and proceeds from the accounts holding the securities, but the Asset Managers state they do not have the right to receive such dividends or proceeds and disclaim ownership associated with those rights.
Does any single managed account own more than 5% of IDEAYA according to this filing?
No. Item 6 specifies that, of the Managed Portfolios collectively, none owns more than 5% of Ideaya common stock, although the parent group’s aggregate beneficial ownership is reported at 8.3%.
