Day One Biopharmaceuticals, Inc. 4 SEC Filings

Filed On	Filing
27 Apr 2026	Form 4: Ai Day1 Llc, 10% owner and 3 others Disposed of 12,929,322 shares (Tender Offer) ($278M) · Disposed of 827,586 Pre-Funded Warrant (right to buy) (Disposition to Issuer) ($17.8M)
23 Apr 2026	Form 4: Bender Jeremy, Director Returned 1,799,031 shares to the issuer · Disposed of 3,031,134 Stock Option (right to buy Common Stock) (Disposition to Issuer) · Disposed of 446,819 Restricted Stock Unit (RSU) (Disposition to Issuer)
23 Apr 2026	Form 4: Vasconcelles Michael, Head of Research and Dev. Returned 4,397 shares to the issuer · Disposed of 517,000 Stock Option (right to buy Common Stock) (Disposition to Issuer) · Disposed of 332,875 Restricted Stock Unit (RSU) (Disposition to Issuer)
23 Apr 2026	Form 4: York Charles N Ii, COO and CFO Returned 312,025 shares to the issuer · Disposed of 1,276,667 Stock Option (right to buy Common Stock) (Disposition to Issuer) · Disposed of 244,125 Restricted Stock Unit (RSU) (Disposition to Issuer)
23 Apr 2026	Form 4: Dubow Adam, Gen Counsel & Secretary Returned 72,694 shares to the issuer · Disposed of 684,000 Stock Option (right to buy Common Stock) (Disposition to Issuer) · Disposed of 146,145 Restricted Stock Unit (RSU) (Disposition to Issuer)
23 Apr 2026	Form 4: Holles Natalie C., Director Returned 57,310 shares to the issuer · Disposed of 201,335 Stock Option (right to buy Common Stock) (Disposition to Issuer) · Disposed of 15,000 Restricted Stock Unit (RSU) (Disposition to Issuer)
23 Apr 2026	Form 4: Ramasastry Saira, Director Returned 40,485 shares to the issuer · Disposed of 208,616 Stock Option (right to buy Common Stock) (Disposition to Issuer) · Disposed of 15,000 Restricted Stock Unit (RSU) (Disposition to Issuer)
23 Apr 2026	Form 4: Josey John A., Director Returned 72,292 shares to the issuer · Disposed of 185,216 Stock Option (right to buy Common Stock) (Disposition to Issuer) · Disposed of 15,000 Restricted Stock Unit (RSU) (Disposition to Issuer)
23 Apr 2026	Form 4: Garland J. Scott, Director Disposed of 169,107 Stock Option (right to buy Common Stock) (Disposition to Issuer) · Disposed of 15,000 Restricted Stock Unit (RSU) (Disposition to Issuer)
23 Apr 2026	Form 4: Dable Habib J, Director Disposed of 121,495 Stock Option (right to buy Common Stock) (Disposition to Issuer) · Disposed of 15,000 Restricted Stock Unit (RSU) (Disposition to Issuer)
23 Apr 2026	Form 4: Grossman William, Director Disposed of 121,495 Stock Option (right to buy Common Stock) (Disposition to Issuer) · Disposed of 15,000 Restricted Stock Unit (RSU) (Disposition to Issuer)
23 Apr 2026	Form 4: Nicholson Garry A, Director Disposed of 126,235 Stock Option (right to buy Common Stock) (Disposition to Issuer) · Disposed of 15,000 Restricted Stock Unit (RSU) (Disposition to Issuer)
23 Apr 2026	Form 4: Merendino Lauren, Chief Commercial Officer Returned 60,157 shares to the issuer · Disposed of 620,200 Stock Option (right to buy Common Stock) (Disposition to Issuer) · Disposed of 154,734 Restricted Stock Unit (RSU) (Disposition to Issuer)
18 Feb 2026	Form 4: Merendino Lauren, Chief Commercial Officer Received 15,162 shares by exercise or conversion · Sold 5,814 shares ($67.4K)
18 Feb 2026	Form 4: Dubow Adam, Gen Counsel & Secretary Received 16,463 shares by exercise or conversion · Sold 6,395 shares ($74.2K)
18 Feb 2026	Form 4: York Charles N Ii, COO and CFO Received 23,375 shares by exercise or conversion · Sold 6,065 shares ($70.4K)
18 Feb 2026	Form 4: Bender Jeremy, Director Received 42,937 shares by exercise or conversion · Sold 15,459 shares ($179K)
18 Feb 2026	Form 4: Vasconcelles Michael, Head of Research and Dev. Received 7,125 shares by exercise or conversion · Sold 2,728 shares ($31.6K)
30 Jan 2026	Form 4: Vasconcelles Michael, Head of Research and Dev. Granted 171,000 Stock Option (right to buy Common Stock) · Granted 114,000 Restricted Stock Units
30 Jan 2026	Form 4: Bender Jeremy, Director Granted 355,000 Stock Option (right to buy Common Stock) · Granted 237,000 Restricted Stock Units

27 Apr 2026

Form 4: Ai Day1 Llc, 10% owner and 3 others

Disposed of 12,929,322 shares (Tender Offer) ($278M) · Disposed of 827,586 Pre-Funded Warrant (right to buy) (Disposition to Issuer) ($17.8M)

23 Apr 2026

Form 4: Bender Jeremy, Director

Returned 1,799,031 shares to the issuer · Disposed of 3,031,134 Stock Option (right to buy Common Stock) (Disposition to Issuer) · Disposed of 446,819 Restricted Stock Unit (RSU) (Disposition to Issuer)

23 Apr 2026

Form 4: Vasconcelles Michael, Head of Research and Dev.

Returned 4,397 shares to the issuer · Disposed of 517,000 Stock Option (right to buy Common Stock) (Disposition to Issuer) · Disposed of 332,875 Restricted Stock Unit (RSU) (Disposition to Issuer)

23 Apr 2026

Form 4: York Charles N Ii, COO and CFO

Returned 312,025 shares to the issuer · Disposed of 1,276,667 Stock Option (right to buy Common Stock) (Disposition to Issuer) · Disposed of 244,125 Restricted Stock Unit (RSU) (Disposition to Issuer)

23 Apr 2026

Form 4: Dubow Adam, Gen Counsel & Secretary

Returned 72,694 shares to the issuer · Disposed of 684,000 Stock Option (right to buy Common Stock) (Disposition to Issuer) · Disposed of 146,145 Restricted Stock Unit (RSU) (Disposition to Issuer)

23 Apr 2026

Form 4: Holles Natalie C., Director

Returned 57,310 shares to the issuer · Disposed of 201,335 Stock Option (right to buy Common Stock) (Disposition to Issuer) · Disposed of 15,000 Restricted Stock Unit (RSU) (Disposition to Issuer)

23 Apr 2026

Form 4: Ramasastry Saira, Director

Returned 40,485 shares to the issuer · Disposed of 208,616 Stock Option (right to buy Common Stock) (Disposition to Issuer) · Disposed of 15,000 Restricted Stock Unit (RSU) (Disposition to Issuer)

23 Apr 2026

Form 4: Josey John A., Director

Returned 72,292 shares to the issuer · Disposed of 185,216 Stock Option (right to buy Common Stock) (Disposition to Issuer) · Disposed of 15,000 Restricted Stock Unit (RSU) (Disposition to Issuer)

23 Apr 2026

Form 4: Garland J. Scott, Director

Disposed of 169,107 Stock Option (right to buy Common Stock) (Disposition to Issuer) · Disposed of 15,000 Restricted Stock Unit (RSU) (Disposition to Issuer)

23 Apr 2026

Form 4: Dable Habib J, Director

Disposed of 121,495 Stock Option (right to buy Common Stock) (Disposition to Issuer) · Disposed of 15,000 Restricted Stock Unit (RSU) (Disposition to Issuer)

23 Apr 2026

Form 4: Grossman William, Director

Disposed of 121,495 Stock Option (right to buy Common Stock) (Disposition to Issuer) · Disposed of 15,000 Restricted Stock Unit (RSU) (Disposition to Issuer)

23 Apr 2026

Form 4: Nicholson Garry A, Director

Disposed of 126,235 Stock Option (right to buy Common Stock) (Disposition to Issuer) · Disposed of 15,000 Restricted Stock Unit (RSU) (Disposition to Issuer)

23 Apr 2026

Form 4: Merendino Lauren, Chief Commercial Officer

Returned 60,157 shares to the issuer · Disposed of 620,200 Stock Option (right to buy Common Stock) (Disposition to Issuer) · Disposed of 154,734 Restricted Stock Unit (RSU) (Disposition to Issuer)

18 Feb 2026

Form 4: Merendino Lauren, Chief Commercial Officer

Received 15,162 shares by exercise or conversion · Sold 5,814 shares ($67.4K)

18 Feb 2026

Form 4: Dubow Adam, Gen Counsel & Secretary

Received 16,463 shares by exercise or conversion · Sold 6,395 shares ($74.2K)

18 Feb 2026

Form 4: York Charles N Ii, COO and CFO

Received 23,375 shares by exercise or conversion · Sold 6,065 shares ($70.4K)

18 Feb 2026

Form 4: Bender Jeremy, Director

Received 42,937 shares by exercise or conversion · Sold 15,459 shares ($179K)