Michael A. Metzger - Sep 8, 2025 Form 4 Insider Report for Syndax Pharmaceuticals Inc (SNDX)

Signature
/s/ Michael A. Metzger
Stock symbol
SNDX
Transactions as of
Sep 8, 2025
Transactions value $
-$867,375
Form type
4
Date filed
9/8/2025, 06:45 PM
Previous filing
Jul 18, 2025

Reporting Owners (1)

Name Relationship Address Signature Signature date CIK
Metzger Michael A Chief Executive Officer, Director C/O SYNDAX PHARMACEUTICALS, INC., 730 3RD AVENUE, FLOOR 9, NEW YORK /s/ Michael A. Metzger 2025-09-08 0001507220

Transactions Table

Type Sym Class Transaction Value $ Shares Change % * Price $ Shares After Date Ownership Footnotes
transaction SNDX Common Stock Options Exercise $1.71M +157K +52.67% $10.90 456K Sep 8, 2025 Direct
transaction SNDX Common Stock Sale -$2.58M -157K -34.5% $16.41 299K Sep 8, 2025 Direct F1, F2

Derivative Securities (e.g., puts, calls, warrants, options, convertible securities)

Type Sym Class Transaction Value $ Shares Change % * Price $ Shares After Date Underlying Class Amount Exercise Price Ownership Footnotes
transaction SNDX Stock options (Right to buy) Options Exercise $0 +157K $0.00 0 Sep 8, 2025 Common Stock 157K $10.90 Direct F3
* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Buy Plan / Sale Plan: These are also open market purchases/sales of shares, but in this case the transaction is part of a trading plan. Rule 10b5-1 allows insiders to setup a trading plan to buy/sell stocks over a certain period of time. Since the purchases/sales are predetermined, this protects the insiders from violating insider trading law.

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).

Explanation of Responses:

Id Content
F1 The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 plan adopted by the Reporting Person solely covering equity grants with expiration dates prior to September 10, 2025. Following the sales reported in this Form 4, the Reporting Person has a total of 1,319,634 options to purchase shares of common stock that are vested and immediately exercisable and a total of 651,241 options to purchase shares of common stock that have not yet vested.
F2 The sale prices ranged from $16.21 to $17.06.
F3 This option is fully vested.