[Form 4] Syndax Pharmaceuticals, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Dennis Podlesak, a director of Syndax Pharmaceuticals, reported option exercises and planned sales under a Rule 10b5-1 plan in mid-August 2025. On 08/14/2025, 08/15/2025 and 08/18/2025 he exercised options with a $7.20 strike to acquire blocks of 19,200, 19,200 and 19,200 shares respectively, and contemporaneously reported sales of those shares under the 10b5-1 plan at prices that ranged across the transactions: $13.30–$16.00 (detailed ranges per date provided). Following the reported transactions the Form 4 shows 210,963 shares beneficially owned after acquisitions and 191,763 after sales, and the filer notes he holds 135,000 vested, exercisable options remaining.

Positive

• Transactions executed under a Rule 10b5-1 plan, which provides an affirmative defense against insider trading allegations
• Sales realized prices well above the $7.20 exercise price (reported ranges $13.30–$16.00), indicating proceeds exceeded strike cost

Negative

• Insider sales reduced direct beneficial ownership from 210,963 to 191,763 shares as reported after the transactions
• No operational or financial context is provided in the filing to explain the timing or rationale beyond the 10b5-1 plan

Insights

Financial Analyst

TL;DR: Routine insider option exercises and planned sales under a 10b5-1 plan; no new material corporate developments disclosed.

These transactions reflect non-derivative share purchases via option exercises at a $7.20 strike and immediate sales executed under a pre-established Rule 10b5-1 plan. The reported sale price ranges ($13.30–$16.00) suggest the sales realized material premiums over the exercise price, but the Form 4 contains no operational or financial results to change company valuation. For investors, this is a disclosure of insider liquidity rather than a signal of corporate performance.

Corporate Governance Expert

TL;DR: Transactions were executed under a documented 10b5-1 plan, indicating compliance with insider-trading rules.

The filing explicitly states the sales were effected pursuant to a Rule 10b5-1 plan covering equity grants expiring before August 21, 2025. That procedural detail reduces regulatory risk from timing allegations. The report also documents remaining equity holdings and vested options, supporting transparent disclosure of the directors beneficial ownership and post-transaction option balances.

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
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Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

X

Check this box to indicate that a 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). See Instruction 10.

1. Name and Address of Reporting Person^*

Podlesak Dennis

(Last) (First) (Middle)

C/O SYNDAX PHARMACEUTICALS, INC.

730 THIRD AVENUE, FLOOR 9

(Street)

NEW YORK NY 10017

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Syndax Pharmaceuticals Inc [ SNDX ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
	Officer (give title below)		Other (specify below)

3. Date of Earliest Transaction (Month/Day/Year)
08/14/2025

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	08/14/2025		M		19,200	A	$7.2	210,963	D
Common Stock	08/14/2025		S(1)		19,200	D	$14.1938(2)	191,763	D
Common Stock	08/15/2025		M		19,200	A	$7.2	210,963	D
Common Stock	08/15/2025		S(1)		19,200	D	$15.5421(3)	191,763	D
Common Stock	08/18/2025		M		19,200	A	$7.2	210,963	D
Common Stock	08/18/2025		S(1)		19,200	D	$15.8422(4)	191,763	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Stock Options (Right to buy)	$7.2	08/14/2025		M			19,200	(5)	08/18/2025	Common Stock	19,200	$0	0	D
Stock Options (Right to buy)	$7.2	08/15/2025		M			14,400	(5)	08/18/2025	Common Stock	14,400	$0	0	D
Stock Options (Right to buy)	$7.2	08/15/2025		M			4,800	(5)	08/20/2025	Common Stock	4,800	$0	0	D
Stock Options (Right to buy)	$7.2	08/18/2025		M			19,200	(5)	08/20/2025	Common Stock	19,200	$0	0	D

Explanation of Responses:

1. 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 August 21, 2025. Following the sales reported in this Form 4, the Reporting Person has a total of 135,000 options to purchase shares of common stock that are vested and immediately exercisable and no unvested options to purchase shares of common stock.

2. The sale prices ranged from $13.30 to $14.80.

3. The sale prices ranged from $14.88 to $15.91.

4. The sale prices ranged from $15.61 to $16.00.

5. This option is fully vested.

	/s/ Michael A. Metzger, Attorney-in-Fact	08/18/2025
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

FAQ

Who filed the Form 4 for SNDX and what is their role?

The Form 4 was filed by Dennis Podlesak, who is identified as a director of Syndax Pharmaceuticals, Inc.

What transactions did the reporting person disclose on the Form 4?

The filer exercised options at a $7.20 strike to acquire multiple blocks of shares (each 19,200 shares on 08/14, 08/15, and 08/18/2025) and reported contemporaneous sales under a 10b5-1 plan.

What sale prices were reported for the SNDX transactions?

The Form 4 reports sale price ranges across the transactions: $13.30–$14.80, $14.88–$15.91, and $15.61–$16.00 for the respective dates.

How many shares and options does the reporting person hold after these transactions?

The filing shows 210,963 shares following acquisitions and 191,763 after the sales. The filer also reports 135,000 vested and immediately exercisable options remaining.

Were the sales planned or discretionary?

Yes. The filing states the sales were effected pursuant to a Rule 10b5-1 plan adopted by the reporting person.