IDEAYA Biosciences CEO sells 26,338 shares

The CEO's exercise was followed by two common-stock sales under a Rule 10b5-1 plan adopted July 7, 2026.

Rhea-AI Filing Summary

At IDEAYA Biosciences, Inc. (IDYA), President and CEO and director Yujiro S. Hata exercised 26,338 stock options on October 6, 2026, at $4.31 per share. He then sold 25,538 common shares at a weighted average sale price of $37.3869 per share and 800 shares at a weighted average sale price of $38.2626 per share; both sales were under a Rule 10b5-1 trading plan adopted July 7, 2026. His reported remaining option position was 23,116 options, expiring February 26, 2028.

Insider Trade Summary 10b5-1

Exercise and Sale: 26,338 shares ($872K approx. pre-tax spread)

Exercise and Sale 4 txns

Insider Hata Yujiro S

Role President and CEO

Sold 26,338 shs ($985K)

Approx. gross sale proceeds $985K

Approx. exercise cost $114K

Approx. pre-tax spread $872K

Type	Security	Shares	Price	Value
Exercise	Stock Option (right to buy) F4	26,338	$0.00	$0.00
Exercise	Common Stock	26,338	$4.31	$114K
Sale	Common Stock F1, F2	25,538	$37.3869	$955K
Sale	Common Stock F1, F3	800	$38.2626	$31K

Holdings After Transaction: Stock Option (right to buy) — 23,116 contracts (Direct); Common Stock — 690,695 shares (Direct)

Footnotes (4)

1. F1. The transactions reported herein were effected pursuant to the Reporting Person's Rule 10b5-1 trading plan, adopted on July 7, 2026, in which the majority of the shares acquired upon the exercise of stock options were granted to the Reporting Person prior to the Issuer's initial public offering and are approaching their expiration date.
2. F2. This transaction was executed in multiple trades in prices ranging from $37.00 to $37.98, inclusive. The price reported in Column 4 above reflects the weighted average sale price. The Reporting Person hereby undertakes to provide to the Securities and Exchange Commission staff, the Issuer, or a security holder of the Issuer, upon request, full information regarding the number of shares sold at each respective price within the range set forth in this footnote.
3. F3. This transaction was executed in multiple trades in prices ranging from $38.23 to $38.34, inclusive. The price reported in Column 4 above reflects the weighted average sale price. The Reporting Person hereby undertakes to provide to the Securities and Exchange Commission staff, the Issuer, or a security holder of the Issuer, upon request, full information regarding the number of shares sold at each respective price within the range set forth in this footnote.
4. F4. The shares subject to the option are fully vested and exercisable.

Key Figures

Stock options exercised: 26,338 options Option exercise price: $4.31 per share Common shares sold: 25,538 shares +5 more

8 metrics

Stock options exercised 26,338 options October 6, 2026

Option exercise price $4.31 per share October 6, 2026

Common shares sold 25,538 shares October 6, 2026

Weighted average sale price $37.3869 per share Sale of 25,538 common shares on October 6, 2026

Common shares sold 800 shares October 6, 2026

Weighted average sale price $38.2626 per share Sale of 800 common shares on October 6, 2026

Remaining stock options 23,116 options Reported following the exercise

Option expiration date February 26, 2028 Reported remaining option position

Key Terms

Rule 10b5-1 trading plan, weighted average sale price, fully vested and exercisable

3 terms

Rule 10b5-1 trading plan regulatory

"Rule 10b5-1 trading plan, adopted on July 7, 2026"

A Rule 10b5-1 trading plan is a pre-arranged schedule that allows company insiders to buy or sell stock at specific times, even if they have inside information. It helps prevent accusations of unfair trading by making these transactions look planned and transparent, rather than sneaky or illegal.

weighted average sale price financial

"reflects the weighted average sale price"

fully vested and exercisable financial

"The shares subject to the option are fully vested and exercisable"

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

How many IDYA shares did its CEO exercise and sell on October 6, 2026?

Yujiro S. Hata exercised 26,338 stock options at $4.31 per share, then sold 25,538 common shares at a weighted average sale price of $37.3869 per share and 800 shares at a weighted average sale price of $38.2626 per share. The sales were made under a Rule 10b5-1 trading plan adopted July 7, 2026.

AI-generated analysis. How Rhea-AI works. Not financial advice.

Form 4 Insider Transactions: What Each Field Means →

See more from StockTitan in Google Search and AI answers. Adds StockTitan as a preferred source · opens Google

Add on Google Not now

Available on EDGAR 10/08/2026 - 07:04 PM Accepted by SEC EDGAR 10/08/2026 - 07:03 PM Learn about SEC filing dates

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).

X

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Hata Yujiro S

(Last) (First) (Middle)

C/O IDEAYA BIOSCIENCES, INC.

5000 SHORELINE COURT, SUITE 300

(Street)

SOUTH SAN FRANCISCO CALIFORNIA 94080

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
IDEAYA Biosciences, Inc. [ IDYA ]

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

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
10/06/2026

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

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

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

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	10/06/2026		M		26,338	A	$4.31	717,033	D
Common Stock	10/06/2026		S(1)		25,538	D	$37.3869(2)	691,495	D
Common Stock	10/06/2026		S(1)		800	D	$38.2626(3)	690,695	D

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
Stock Option (right to buy)	$4.31	10/06/2026		M			26,338	(4)	02/26/2028	Common Stock	26,338	$0	23,116	D

Explanation of Responses:

1. The transactions reported herein were effected pursuant to the Reporting Person's Rule 10b5-1 trading plan, adopted on July 7, 2026, in which the majority of the shares acquired upon the exercise of stock options were granted to the Reporting Person prior to the Issuer's initial public offering and are approaching their expiration date.

2. This transaction was executed in multiple trades in prices ranging from $37.00 to $37.98, inclusive. The price reported in Column 4 above reflects the weighted average sale price. The Reporting Person hereby undertakes to provide to the Securities and Exchange Commission staff, the Issuer, or a security holder of the Issuer, upon request, full information regarding the number of shares sold at each respective price within the range set forth in this footnote.

3. This transaction was executed in multiple trades in prices ranging from $38.23 to $38.34, inclusive. The price reported in Column 4 above reflects the weighted average sale price. The Reporting Person hereby undertakes to provide to the Securities and Exchange Commission staff, the Issuer, or a security holder of the Issuer, upon request, full information regarding the number of shares sold at each respective price within the range set forth in this footnote.

4. The shares subject to the option are fully vested and exercisable.

	/s/ Andres Ruiz Briseno, as Attorney-in-Fact for Yujiro Hata	10/08/2026
	** 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).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)