Major holder exits Day One Biopharmaceuticals (DAWN) in $21.50 cash tender

Rhea-AI Filing Summary

Day One Biopharmaceuticals, Inc. large stockholder AI Day1 LLC and its affiliated reporting persons, including Len Blavatnik, have exited their position in the company. They tendered all shares into Servier Detroit Inc.’s cash tender offer at $21.50 per share, with pre-funded warrants converted into $21.4999 per warrant in cash. Following settlement on April 23, 2026, the group reports beneficial ownership of 0% of Day One’s common stock and confirms they ceased to be holders of more than five percent of the shares on that date.

Insights

Equity ownership & M&A analyst

Major shareholder exits DAWN after tender offer closes.

The filing shows AI Day1 LLC and affiliated Access Industries entities, including Len Blavatnik, tendered all Day One Biopharmaceuticals shares into Servier Detroit Inc.’s cash offer at $21.50 per share. Pre-funded warrants were similarly cashed out at $21.4999 per warrant.

As of April 23, 2026, these reporting persons hold no beneficial ownership and have fallen below the five percent threshold. This aligns with the consummation of the broader merger transaction, confirming that a significant legacy shareholder has fully exited its economic stake.

Key Figures

Tender offer price: $21.50 per share Pre-funded warrant cash amount: $21.4999 per warrant Beneficial ownership after transactions: 0.00 shares +2 more

5 metrics

Tender offer price $21.50 per share Cash consideration per common share in Servier Detroit tender offer

Pre-funded warrant cash amount $21.4999 per warrant Cash received per pre-funded warrant upon merger consummation

Beneficial ownership after transactions 0.00 shares Shares beneficially owned by each reporting person after tender

Post-transaction ownership percentage 0.00% Percent of DAWN common stock reported by each person

Date ceased to be >5% holder April 23, 2026 Reporting persons no longer beneficial owners above five percent

Key Terms

Tender Offer, Schedule 13D, beneficial ownership, pre-funded warrant, +1 more

5 terms

Tender Offer financial

"pursuant to the tender offer by Servier Detroit Inc. ("Purchaser")"

A tender offer is a proposal made by a person or company to buy shares from existing shareholders at a set price, usually higher than the current market value, within a specific time frame. It matters to investors because it can lead to a change in ownership or control of a company, and shareholders must decide whether to sell their shares at the offered price.

Schedule 13D regulatory

"The filed with the Securities and Exchange Commission ("SEC") on June 9, 2021"

A Schedule 13D is a legal document that investors file with regulators when they buy a large enough stake in a company to potentially influence its management or decisions. It provides details about the investor’s intention, ownership stake, and plans, helping other investors understand who is gaining control and what their motives might be.

beneficial ownership financial

"the Reporting Persons no longer have any beneficial ownership in the 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.

pre-funded warrant financial

"each pre-funded warrant held by AI Day1 to purchase Common Stock was converted"

A pre-funded warrant is a financial instrument that gives the holder the right to buy shares of a company's stock at a set price, with most of the purchase cost already paid upfront. It functions like a nearly fully paid option, allowing investors to secure shares quickly while minimizing the amount of additional money they need to invest later. This helps investors gain ownership rights efficiently, often used to avoid certain regulatory restrictions or to prepare for future stock purchases.

Schedule TO regulatory

"Offer to Purchase and related Letter of Transmittal filed with the SEC on Schedule TO"

A phrase indicating that a company plans or intends to hold an event, publish information, or take an action at a specified future time, but that the timing is not guaranteed and may change. For investors it signals an expected milestone—like an earnings call, product launch, or filing—so think of it as a calendar note rather than a firm promise; timing shifts can affect trading, expectations, and planning.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 6)

Day One Biopharmaceuticals, Inc.

(Name of Issuer)

Common Stock, par value $0.0001 per share

(Title of Class of Securities)

23954D109

(CUSIP Number)

Alejandro Moreno
c/o Access Industries, Inc., 40 West 57th Street, 28th Floor
New York, NY, 10019
(212) 247-6400

Langhorne S. Perrow
c/o Access Industries, Inc., 40 West 57th Street, 28th Floor
New York, NY, 10019
(212) 247-6400

Nicholas P. Pellicani
Debevoise & Plimpton LLP, The Northcliffe, 28 Tudor St.
London, X0, EC4Y 0AY
44 20 7786 9000

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

04/23/2026

(Date of Event Which Requires Filing of This Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.

The information required on the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

schemaVersion:

SCHEDULE 13D

CUSIP Number(s): 23954D109

1

Name of reporting person

AI Day1 LLC

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

AF

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 0.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 0.00

11

Aggregate amount beneficially owned by each reporting person

0.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

0.00 %

14

Type of Reporting Person (See Instructions)

OO

SCHEDULE 13D

CUSIP Number(s): 23954D109

1

Name of reporting person

Access Industries Holdings LLC

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

AF

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 0.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 0.00

11

Aggregate amount beneficially owned by each reporting person

0.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

0.00 %

14

Type of Reporting Person (See Instructions)

OO

SCHEDULE 13D

CUSIP Number(s): 23954D109

1

Name of reporting person

Access Industries Management, LLC

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

AF

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 0.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 0.00

11

Aggregate amount beneficially owned by each reporting person

0.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

0.00 %

14

Type of Reporting Person (See Instructions)

OO

SCHEDULE 13D

CUSIP Number(s): 23954D109

1

Name of reporting person

Len Blavatnik

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

AF

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 0.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 0.00

11

Aggregate amount beneficially owned by each reporting person

0.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

0.00 %

14

Type of Reporting Person (See Instructions)

IN

SCHEDULE 13D

Item 1.	Security and Issuer
(a)	Title of Class of Securities: Common Stock, par value $0.0001 per share
(b)	Name of Issuer: Day One Biopharmaceuticals, Inc.
(c)	Address of Issuer's Principal Executive Offices: 1800 Sierra Point Parkway, Suite 200, Brisbane, CALIFORNIA , 94005.
Item 1 Comment: This Amendment No. 6 to Schedule 13D is being filed by AI Day1 LLC ("AI Day1"), Access Industries Holdings LLC ("AIH"), Access Industries Management, LLC ("AIM") and Len Blavatnik (collectively, the "Reporting Persons", and each, a "Reporting Person"), in respect of the common stock, par value $0.0001 per share (the "Common Stock"), of Day One Biopharmaceuticals, Inc. (the "Issuer"). The Schedule 13D filed with the Securities and Exchange Commission ("SEC") on June 9, 2021, as amended and supplemented by Amendment No. 1 to the Schedule 13D filed by the Reporting Persons with the SEC on June 21, 2022, Amendment No. 2 to the Schedule 13D filed by the Reporting Persons with the SEC on June 12, 2023, Amendment No. 3 to the Schedule 13D filed by the Reporting Persons with the SEC on October 20, 2023, Amendment No. 4 to the Schedule 13D filed by the Reporting Persons with the SEC on August 1, 2024 and Amendment No. 5 to the Schedule 13D filed by the Reporting Persons with the SEC on April 13, 2026 (together, the "Schedule") is hereby amended and supplemented by the Reporting Persons as set forth below in this Amendment No. 6. This amendment is filed by the Reporting Persons in accordance with Rule 13d-2 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), and refers only to information that has materially changed since the filing of the Schedule. The items identified below, or the particular paragraphs of such items which are identified below, are amended as set forth below. Unless otherwise indicated, all capitalized terms used and not defined herein have the respective meanings assigned to them in the Schedule.
Item 4.	Purpose of Transaction
	The disclosure in Item 4 is hereby amended and supplemented by adding the following at the end thereof: On April 9, 2026, AI Day1 tendered all of its shares of Common Stock pursuant to the tender offer by Servier Detroit Inc. ("Purchaser") to purchase all of the issued and outstanding shares of Common Stock for $21.50 per share in cash, upon the terms and subject to the conditions described in the Offer to Purchase and related Letter of Transmittal filed with the SEC on Schedule TO on March 26, 2026 (the "Tender Offer"). Such shares were accepted by the Purchaser on April 23, 2026. On April 23, 2026, in connection with the consummation of the merger, each pre-funded warrant held by AI Day1 to purchase Common Stock was converted into the right to receive $21.4999 per warrant in cash.
Item 5.	Interest in Securities of the Issuer
(a)	Item 5 of the Schedule 13D is hereby amended and restated as follows: As a result of the Tender Offer, the Reporting Persons no longer have any beneficial ownership in the Common Stock.
(c)	The information set forth in Item 4 of this Schedule 13D is incorporated by reference herein.
(d)	Not applicable.
(e)	The Reporting Persons ceased to be beneficial owners of more than five percent of the Issuer's Common Stock on April 23, 2026.

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.

AI Day1 LLC

Signature:	/s/ Alejandro Moreno
Name/Title:	By: Access Industries Management, LLC, its Manager; its Executive Vice President/Alejandro Moreno
Date:	04/27/2026

Access Industries Holdings LLC

Signature:	/s/ Alejandro Moreno
Name/Title:	By: Access Industries Management, LLC, its Manager; its Executive Vice President/Alejandro Moreno
Date:	04/27/2026

Access Industries Management, LLC

Signature:	/s/ Alejandro Moreno
Name/Title:	By: Executive Vice President/Alejandro Moreno
Date:	04/27/2026

Len Blavatnik

Signature:	*
Name/Title:	Len Blavatnik
Date:	04/27/2026

Comments accompanying signature:

* The undersigned, by signing his name hereto, executes this Amendment No. 6 to Schedule 13D pursuant to the Limited Power of Attorney executed on behalf of Mr. Blavatnik and filed herewith. By: /s/ Alejandro Moreno Name: Alejandro Moreno Attorney-in-Fact

FAQ

What does this Schedule 13D/A Amendment mean for Day One Biopharmaceuticals (DAWN)?

It shows a major shareholder group, including AI Day1 LLC and Len Blavatnik, has fully exited its DAWN stake. All shares were tendered into Servier Detroit Inc.’s cash offer and warrants were cashed out, leaving the group with 0% beneficial ownership.

At what price were DAWN shares tendered by AI Day1 LLC and affiliates?

The shares were tendered at a cash price of $21.50 per share. This price comes from Servier Detroit Inc.’s tender offer to acquire all outstanding Day One Biopharmaceuticals common stock, as referenced in the Schedule 13D/A amendment.

What happened to the pre-funded warrants held by AI Day1 related to DAWN?

Each pre-funded warrant to purchase Day One common stock was converted into the right to receive $21.4999 in cash. This occurred on April 23, 2026, in connection with the consummation of the merger following the tender offer.

Do the reporting persons still own any Day One Biopharmaceuticals (DAWN) stock?

No. The amendment states the reporting persons now have 0.00 shares and 0.00% beneficial ownership of DAWN common stock. They ceased to be beneficial owners of more than five percent of the shares on April 23, 2026.

Who are the reporting persons named in this DAWN Schedule 13D/A amendment?

The reporting persons are AI Day1 LLC, Access Industries Holdings LLC, Access Industries Management, LLC, and Len Blavatnik. They previously reported significant ownership in Day One Biopharmaceuticals but now report zero beneficial ownership after the tender offer.

When did the tendered DAWN shares get accepted in the Servier Detroit tender offer?

The filing notes that the tendered Day One shares were accepted by Servier Detroit Inc. on April 23, 2026. That same date marks when the reporting persons ceased to be beneficial owners of more than five percent of DAWN common stock.