Day One Biopharmaceuticals, Inc.

Overview

• IndustryPharmaceutical Preparations¹
• HeadquartersBrisbane, California¹
• Incorporated inDE²
• Business address1800 Sierra Point Parkway, Suite 200, Brisbane, Ca 94005²
• Filer categoryLarge accelerated filer²

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Day One Biopharmaceuticals, Inc., or the Company or Day One, is a biopharmaceutical company dedicated to developing and commercializing targeted therapies for people of all ages with life-threatening diseases.⁴ From its latest annual report

Corporate structure

Day One Biopharmaceuticals, Inc. sits at the top of its group. 3 entities, 1 country on record. Switch between the flow chart and the network, and select any entity to see its details.

Built from subsidiaries listed in Exhibit 21 of annual reports filed with the SEC; major holders from Schedules 13D and 13G. Each entity in the chart links to its source.

What it owns

What Day One Biopharmaceuticals, Inc. reports owning in its annual reports to the SEC: buildings, land and equipment, real estate and locations, investments, intangible assets and inventory, at the end of its latest fiscal year and a year before.

Property and equipment

Investments

Intangibles and goodwill

Inventory

Properties, in its own words

Our principal executive office is located in Brisbane, California, where we lease approximately 19,000 square feet of office space. The lease expires in January 2032. There is no option to extend the lease term nor is there an option to terminate the lease prior to its expiration. We believe these facilities are sufficient to meet our ongoing needs and that, if we require additional space, we will be able to obtain additional facilities on commercially reasonable terms.

Item 2 of the 10-K filed Feb 24, 2026.⁴

Leadership

Who has led Day One Biopharmaceuticals, Inc., and when. Pick a name to see everywhere that person has worked.

• Chief executive officerJeremy Bender May 26, 2021 to now¹³
• Chief financial officerCharles N. York Ii. May 26, 2021 to now¹⁴
• Chief operating officerCharles N. York Ii. May 26, 2021 to now¹⁴

Subsidiaries and ownership

Subsidiaries (Exhibit 21)

• Mersana Securities Corp. Massachusetts³
• Mersana Therapeutics, Inc. Delaware³

The subsidiaries the company lists in Exhibit 21 of its annual report, as filed.

Former names

• Day One Biopharmaceuticals Holding Co LLCFeb 16, 2021 to May 26, 2021²

Timeline

1. Apr 23, 20268-K Ended a material agreement; Completed an acquisition or sale; Listing notice or transfer³⁰
2. Mar 9, 20268-K Financial statements and exhibits³¹
3. Mar 6, 20268-K Entered a material agreement; Other events³²
4. Mar 2, 20268-K Regulation FD disclosure³³
5. Feb 24, 20268-K Results of operations; Regulation FD disclosure³⁴
6. Jan 12, 20268-K Results of operations; Regulation FD disclosure³⁵
7. Jan 6, 20268-K Entered a material agreement; Completed an acquisition or sale; Regulation FD disclosure³⁶
8. Nov 24, 20258-K Regulation FD disclosure; Other events³⁷
9. Nov 13, 20258-K Entered a material agreement; Regulation FD disclosure³⁸
10. Nov 4, 20258-K Results of operations; Regulation FD disclosure³⁹
11. Oct 10, 20258-K Executive or director change⁴⁰
12. Aug 5, 20258-K Results of operations; Regulation FD disclosure⁴¹
13. May 26, 2021New chief executive Jeremy Bender becomes CEO¹³

Calendar

When it reported results

1. Feb 24, 2026Reported quarterly or annual results³⁴
2. Jan 12, 2026Reported quarterly or annual results³⁵
3. Nov 4, 2025Reported quarterly or annual results³⁹
4. Aug 5, 2025Reported quarterly or annual results⁴¹
5. May 6, 2025Reported quarterly or annual results⁴²
6. Feb 25, 2025Reported quarterly or annual results⁴³
7. Jan 13, 2025Reported quarterly or annual results⁴⁴
8. Oct 30, 2024Reported quarterly or annual results⁴⁵

Upcoming dates from Nasdaq's calendar; past results from the company's 8-K filings (Item 2.02). The full markets calendar

Filings

436 filings to the SEC since October 2021: 7 annual reports, 13 quarterly reports, 62 major events, 229 insider forms, 37 large holders, 88 other. The latest 20:

1. May 15, 2026SCHEDULE 13G/A EDGAR
2. May 14, 2026SCHEDULE 13G/A EDGAR
3. May 4, 202615-12G EDGAR
4. Apr 27, 2026SCHEDULE 13D/A EDGAR
5. Apr 27, 20264 EDGAR
6. Apr 23, 20264 EDGAR
7. Apr 23, 20264 EDGAR
8. Apr 23, 20264 EDGAR
9. Apr 23, 20264 EDGAR
10. Apr 23, 20264 EDGAR
11. Apr 23, 20264 EDGAR
12. Apr 23, 20264 EDGAR
13. Apr 23, 20264 EDGAR
14. Apr 23, 20264 EDGAR
15. Apr 23, 20264 EDGAR
16. Apr 23, 20264 EDGAR
17. Apr 23, 20264 EDGAR
18. Apr 23, 2026S-8 POS EDGAR
19. Apr 23, 2026S-8 POS EDGAR
20. Apr 23, 2026S-8 POS EDGAR

Every filing from the last five years, summarized. The full record is on SEC EDGAR.

Insider trades

161 open-market trades by officers, directors and large owners since October 2021: 10 buys and 151 sales. Grants, option exercises and gifts are left out.

From Forms 4 filed with the SEC.

Major holders

Investors who own more than 5% of the shares must tell the SEC: a 13D if they may seek to influence the company, a 13G if they hold passively.

• Vestal Point Capital, LPSCHEDULE 13G/A, 2 filings Feb 17, 2026 to May 15, 2026⁴⁶
• Atlas Venture Fund XI, L.P.SCHEDULE 13G/A, 5 filings Feb 11, 2022 to May 14, 2026⁴⁷
• AI Day1 LLCSCHEDULE 13D/A, 6 filings Jun 21, 2022 to Apr 27, 2026⁴⁸
• FMR LLCSCHEDULE 13G/A, 11 filings Sep 12, 2022 to Apr 7, 2026⁴⁹
• VANGUARD GROUP INCSCHEDULE 13G/A, 2 filings Feb 13, 2024 to Mar 26, 2026⁵⁰
• GLAZER CAPITAL, LLCSCHEDULE 13G, 1 filing Mar 19, 2026⁵¹
• RA CAPITAL MANAGEMENT, L.P.SCHEDULE 13G/A, 4 filings Feb 14, 2023 to Aug 14, 2025⁵²
• Canaan XI L.P.SC 13D/A, 5 filings Dec 22, 2021 to Nov 2, 2022⁵³
• Takeda Pharmaceutical CompanySC 13G, 1 filing Jan 14, 2022⁵⁴

Executive pay

What the company paid its top executives, from the summary compensation table in its proxy statement. Total pay includes salary, bonus, stock and option awards and other pay, as the company valued them.

SEC filer profile

How Day One Biopharmaceuticals, Inc. is registered with the Securities and Exchange Commission, from its EDGAR record and the cover page of its latest annual report.

• Name on EDGARDay One Biopharmaceuticals, Inc.¹
• CIK0001845337
• Employer ID (EIN)83-2415215⁴
• Filer statusLarge accelerated filer not an emerging growth company; not a smaller reporting company; not a shell company⁴
• Incorporated inDelaware⁴
• Fiscal year endsDecember 31¹
• Industry code (SIC)2834 Pharmaceutical Preparations¹
• SEC reviewing officeOffice of Life Sciences, Division of Corporation Finance¹
• Business address1800 Sierra Point Parkway, Suite 200, Brisbane, CA 94005¹
• Phone650 484-0899¹
• Shares outstanding103,334,169 as of Apr 15, 2026⁶
• Public float$567.0M as of Jun 30, 2025⁴
• AuditorPricewaterhouseCoopers LLP, Los Angeles, California PCAOB ID 238; it also attests to the company’s internal control over financial reporting⁴
• On EDGAR sinceFeb 16, 2021¹
• Filings493 in all: 4 (227), 8-K (63), 144 (39), 3 (20), 10-Q (14), SCHEDULE 13G/A (11), SC 13G/A (10), SC 13D/A (9)¹
  All 46 form types

  SC 13G (7), SC TO-C (7), S-8 (6), S-8 POS (6), SC TO-T/A (6), 10-K (5), CORRESP (5), 424B5 (4), DEF 14A (4), DEFA14A (4), ARS (3), SC 14D9/A (3), SCHEDULE 13G (3), UPLOAD (3), 10-K/A (2), 5 (2), EFFECT (2), POSASR (2), S-1/A (2), S-3ASR (2), SC 13D (2), SC TO-T (2), SCHEDULE 13D/A (2), SEC STAFF LETTER (2), 15-12G (1), 25-NSE (1), 4/A (1), 424B4 (1), 8-A12B (1), 8-K/A (1), CERT (1), D (1), DRS (1), PRE 14A (1), S-1 (1), S-3 (1), SC 14D9 (1), SC14D9C (1)

• Latest filingsAnnual report (10-K) Feb 24, 2026
  Quarterly report (10-Q) Nov 4, 2025
  Proxy statement (DEF 14A) Apr 11, 2025
  Latest 8-K (8-K) Apr 23, 2026

Securities registered for trading

From the cover page of the 10-K filed Feb 24, 2026 (Section 12(b) of the Exchange Act).⁴

Risk factors and legal proceedings

The risks Day One Biopharmaceuticals, Inc. names in Item 1A of its 10-K filed Feb 24, 2026: 74 risks under these headings, as written.⁴

• Risks Related to Our Financial Position
• We are a commercial-stage biopharmaceutical company with a limited operating history in the initial stages of the commercialization our product OJEMDA, which may make it difficult for investors to evaluate our current business and likelihood of success and viability.
• We have incurred significant net losses since our inception. We expect to incur continued losses for the foreseeable future and may never achieve or maintain profitability.
• Our near-term revenues are highly dependent on the successful commercialization of OJEMDA, which received marketing approval in April 2024 from the FDA for the treatment of patients 6 months of age and older with relapsed or refractory pLGG harboring a BRAF fusion or rearrangement, or BRAF V600 mutation. To the extent that OJEMDA is not commercially successful, our business, financial condition and results of operations would be materially and adversely affected and the price of our common stock would decline.
• Our ability to generate revenue and achieve profitability depends significantly on our ability to achieve several objectives relating to the development and commercialization of OJEMDA, Emi-Le, DAY301 and our future product candidates.
• We may require additional capital to finance our operations and achieve our goals. If we are unable to raise capital when needed or on terms acceptable to us, we may be forced to delay, reduce or eliminate our research or product development programs, any future commercialization efforts or other operations.
• Risks Related to Development and Commercialization of OJEMDA and our Product Candidates
• Clinical trials are very expensive, time-consuming and difficult to design and implement, and involve uncertain outcomes. Furthermore, results of earlier preclinical studies and clinical trials may not be predictive of results of future preclinical studies or clinical trials. OJEMDA and our product candidates may not have favorable results in later clinical trials, if any, and not all of our product candidates will receive marketing authorization. If we fail to demonstrate the safety and effectiveness of our product candidates, our reputation may be harmed and our business will suffer.
• OJEMDA has only been studied in a limited number of patients. Following commercial launch, OJEMDA is now available to a much larger number of patients, and we do not know whether the results of OJEMDA’s use in such larger number of patients will be consistent with the results from our clinical studies.
• We may rely on data from investigator-initiated studies, as we did for the Phase 1 clinical trial, and we do not control the trial operations or reporting of the results of such trials.
• Our clinical trials may be suspended, delayed or fail to adequately demonstrate the safety and effectiveness of OJEMDA and our product candidates, which would prevent or delay development, marketing authorization and commercialization.
• We cannot predict the outcome of our clinical trials, nor can we guarantee that the data we generate from our clinical trials will be acceptable to regulatory authorities so as to support marketing authorization.

Legal proceedings

The Company, from time to time, may be party to litigation arising in the ordinary course of business. The Company is not subject to any material legal proceedings, and to the best of its knowledge, no material legal proceedings are currently pending or threatened.

The opening of Item 3, Legal Proceedings.⁴