IDEAYA Biosciences, Inc.

The holders of common stock are also entitled to receive dividends whenever funds are legally available and when declared by the Company s board of directors.

SEC original ↗IDEAYA Biosciences, Inc. — 10-Q Quarterly report10-QAug 4, 2026

The Company has not declared any dividends to date.

SEC original ↗IDEAYA Biosciences, Inc. — 10-Q Quarterly report10-QAug 4, 2026

The warrants are classified as equity because they are freestanding financial instruments that are legally detachable and separately exercisable from the equity instruments, are immediately exercisable, do not embody an obligation for the Company to repurchase its shares, are indexed to the Company s common stock and meet the equity classification criteria.

SEC original ↗IDEAYA Biosciences, Inc. — 10-Q Quarterly report10-QAug 4, 2026

Black-Scholes Assumptions The fair values of options were calculated using the assumptions set forth below: Three Months Ended June 30, Six Months Ended 2026 2025 2026 2025 Expected term 5.5 - 6.1 years 5.5 - 6.1 years 5.5 - 6.1 years 5.5 - 6.1 years Expected volatility 60.2 % - 67.6 % 72.6 % - 75.8 % 60.2 % - 70.5 % 72.6 % - 76.3 % Risk-free interest rate 4.1 % - 4.2 % 3.8 % - 4.1 % 3.7 % - 4.2 % 3.8 % - 4.4 % Dividend yield 0 % 0 % 0 % 0 % Expected term .

SEC original ↗IDEAYA Biosciences, Inc. — 10-Q Quarterly report10-QAug 4, 2026

The Company has not paid and does not anticipate paying any dividends in the near future.

SEC original ↗IDEAYA Biosciences, Inc. — 10-Q Quarterly report10-QAug 4, 2026

Accordingly, the Company has estimated the dividend yield to be zero .

SEC original ↗IDEAYA Biosciences, Inc. — 10-Q Quarterly report10-QAug 4, 2026

We are also excited to host Exhibit 99.1 our 10-year Anniversary R&D Day in New York City on September 8 th , where we will present multiple data updates across our potential first-in-class clinical pipeline and highlight our strategic vision and pioneering research in cancer biology and drug discovery, said Yujiro S.

SEC original ↗IDEAYA Biosciences, Inc. — Earnings release (8-K exhibit)EX-99Aug 5, 2025

• In April 2025, the companies announced expansion of the IDE397 and Trodelvy (sacituzumab govitecan-hziy) combination trial in NSCLC.

SEC original ↗IDEAYA Biosciences, Inc. — Earnings release (8-K exhibit)EX-99Aug 5, 2025

IDEAYA will provide initial Phase 1 safety and efficacy data from two expansion cohorts in the IDE397 and Trodelvy (sacituzumab govitecan-hziy) combination trial in MTAP-deletion UC patients at the company’s R&D Day September 8 th , with additional data targeted for a medical conference in the first half of 2026.

SEC original ↗IDEAYA Biosciences, Inc. — Earnings release (8-K exhibit)EX-99Aug 5, 2025

The presentation will include data from the dose escalation and multiple expansion doses.

SEC original ↗IDEAYA Biosciences, Inc. — Earnings release (8-K exhibit)EX-99Aug 5, 2025

• Phase 2 expansion in HRD-positive solid tumors would trigger a $10 million milestone payment from GSK.

SEC original ↗IDEAYA Biosciences, Inc. — Earnings release (8-K exhibit)EX-99Aug 5, 2025

Such forward-looking statements involve substantial risks and Exhibit 99.1 uncertainties that could cause IDEAYA's preclinical and clinical development programs, future results, performance or achievements to differ significantly from those expressed or implied by the forward-looking statements.

SEC original ↗IDEAYA Biosciences, Inc. — Earnings release (8-K exhibit)EX-99Aug 5, 2025

Such risks and uncertainties include, among others, the uncertainties inherent in the drug development process, including IDEAYA's programs' early stage of development, the process of designing and conducting preclinical and clinical trials, the regulatory approval processes, the timing of regulatory filings, the challenges associated with manufacturing drug products, IDEAYA's ability to successfully establish, protect and defend its intellectual property, and other matters that could affect the sufficiency of existing cash to fund operations.

SEC original ↗IDEAYA Biosciences, Inc. — Earnings release (8-K exhibit)EX-99Aug 5, 2025

For a further description of the risks and uncertainties that could cause actual results to differ from those expressed in these forward-looking statements, as well as risks relating to the business of IDEAYA in general, see IDEAYA's Annual Report on Form 10-K dated February 18, 2025 and any current and periodic reports filed with the U.

SEC original ↗IDEAYA Biosciences, Inc. — Earnings release (8-K exhibit)EX-99Aug 5, 2025

These statements involve known and unknown risks, uncertainties and other important factors that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements.

SEC original ↗IDEAYA Biosciences, Inc. — 10-Q Quarterly report10-QAug 4, 2026

These forward-looking statements speak only as of the date of this Quarterly Report on Form 10-Q and are subject to a number of risks, uncertainties and assumptions described under the sections in this Quarterly Report on Form 10-Q entitled Risk Factors and Management s Discussion and Analysis of Financial Condition and Results of Operations and elsewhere in this Quarterly Report on Form 10-Q.

SEC original ↗IDEAYA Biosciences, Inc. — 10-Q Quarterly report10-QAug 4, 2026

New risk factors and uncertainties may emerge from time to time, and it is not possible for management to predict all risk factors and uncertainties.

SEC original ↗IDEAYA Biosciences, Inc. — 10-Q Quarterly report10-QAug 4, 2026