Were the Syndax (SNDX) CEO’s share sales made under a Rule 10b5-1 plan?

Yes. A footnote states the sales were effected under a pre-established Rule 10b5-1 trading plan. Such plans allow insiders to schedule trades in advance, helping separate routine liquidity events from discretionary market-timing decisions.

Syndax (SNDX) CEO Metzger exercises options and sells 32,375 shares under 10b5-1 plan

Filing Impact

(Neutral)

Filing Sentiment

(Neutral)

Form Type

Rhea-AI Filing Summary

Syndax Pharmaceuticals Chief Executive Officer Michael A. Metzger reported an exercise-and-sale transaction in company common stock. He exercised stock options for 32,375 shares at $6.38 per share and sold 32,375 shares in open-market trades at an average of $24.2402 per share.

The sales were made under a pre-established Rule 10b5-1 trading plan. After these transactions, Metzger directly holds 484,843 common shares and retains 1,564,551 vested options that are immediately exercisable, plus 813,949 additional options that have not yet vested.

Insider Trade Summary 10b5-1

Net Seller: 32,375 shares ($784,776)

Net Sell 3 txns

Insider Metzger Michael A

Role Chief Executive Officer

Sold 32,375 shs ($785K)

Type	Security	Shares	Price	Value
Exercise	Stock Option (Right to buy)	32,375	$0.00	--
Exercise	Common Stock	32,375	$6.38	$207K
Sale	Common Stock	32,375	$24.2402	$785K

Holdings After Transaction: Stock Option (Right to buy) — 0 shares (Direct, null); Common Stock — 517,218 shares (Direct, null)

Footnotes (1)

The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 plan adopted by the Reporting Person. Following the sales reported in this Form 4, the Reporting Person has a total of 1,564,551 options to purchase shares of common stock that are vested and immediately exercisable and a total of 813,949 options to purchase shares of common stock that have not yet vested. The sale prices ranged from $24.00 to $24.43 This option is fully vested.

Key Figures

Shares sold: 32,375 shares Average sale price: $24.2402 per share Option exercise size: 32,375 shares +4 more

7 metrics

Shares sold 32,375 shares Open-market sale of common stock at $24.2402 on 2026-07-08

Average sale price $24.2402 per share Common stock sales on 2026-07-08

Option exercise size 32,375 shares Stock options exercised at $6.38 per share

Option exercise price $6.38 per share Stock option (right to buy) converted into common stock

Shares held after 484,843 shares Direct common stock ownership after transactions

Vested options remaining 1,564,551 options Vested and immediately exercisable options held after sale

Unvested options remaining 813,949 options Options to purchase common stock that have not yet vested

Key Terms

Rule 10b5-1 plan, open-market sale, Stock Option (Right to buy), vested and immediately exercisable, +1 more

5 terms

Rule 10b5-1 plan regulatory

"The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 plan adopted by the Reporting Person."

A Rule 10b5-1 plan is a prearranged, written schedule that lets corporate insiders buy or sell company stock at set times or amounts, even if they later learn material nonpublic information. Think of it like setting an automatic thermostat for trades: it creates a clear record that trades were planned in advance, reducing the risk of insider-trading accusations and helping investors trust that insider transactions are routine rather than based on secret information.

open-market sale financial

"transaction_action": "open-market sale""

An open-market sale is when a shareholder sells existing shares directly on a public exchange to any willing buyer, rather than through a private deal. Think of it like putting goods on a busy market stall where price is set by supply and demand; for investors it matters because such sales increase available supply, can put short-term downward pressure on the stock price, and signal changes in liquidity or investor confidence.

Stock Option (Right to buy) financial

""security_title": "Stock Option (Right to buy)""

vested and immediately exercisable financial

"a total of 1,564,551 options to purchase shares of common stock that are vested and immediately exercisable"

derivative exercise/conversion financial

""transaction_action": "derivative exercise/conversion""

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Form 4 Insider Transactions: What Each Field Means →

Available on EDGAR 07/09/2026 - 04:54 PM Accepted by SEC EDGAR 07/09/2026 - 04:54 PM

FAQ

What insider transaction did Syndax Pharmaceuticals (SNDX) report for its CEO?

Syndax Pharmaceuticals CEO Michael A. Metzger exercised options for 32,375 shares at $6.38 and sold 32,375 common shares at an average of $24.2402. The Form 4 describes this as an open-market sale combined with a derivative option exercise.

How many Syndax (SNDX) shares did the CEO sell in this Form 4 filing?

The CEO sold 32,375 shares of Syndax common stock in open-market transactions. The reported sale prices ranged from $24.00 to $24.43, with a weighted average price of $24.2402 per share, according to the Form 4 disclosure and accompanying footnote.

At what price did the Syndax (SNDX) CEO exercise his stock options?

Michael A. Metzger exercised stock options covering 32,375 shares at a strike price of $6.38 per share. These options were fully vested at the time of exercise, and the corresponding derivative position was reduced to zero after the transaction.

How many Syndax (SNDX) shares does the CEO hold after the reported transactions?

Following the reported transactions, the CEO directly holds 484,843 shares of Syndax common stock. This figure reflects his ownership after exercising 32,375 options and selling 32,375 shares in open-market transactions on the same date.

What stock option position does the Syndax (SNDX) CEO retain after this Form 4?

After the reported exercise, the CEO retains 1,564,551 vested options that are immediately exercisable and 813,949 unvested options. The specific option covering 32,375 shares reported here is fully exercised, leaving no remaining balance for that grant.

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
Estimated average burden
hours per response:			0.5

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

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^*

Metzger Michael A

(Last)

(First)

(Middle)

C/O SYNDAX PHARMACEUTICALS, INC.

730 3RD AVENUE, FLOOR 9

(Street)

NEW YORK

10017

(City)

(State)

(Zip)

UNITED STATES

(Country)

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
X	Officer (give title below)	Other (specify below)
	Chief Executive Officer

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
07/08/2026

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

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

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

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)
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
Common Stock	07/08/2026		M		32,375	A	$6.38	517,218	D
Common Stock	07/08/2026		S⁽¹⁾		32,375	D	$24.2402⁽²⁾	484,843	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)
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)	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)		10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
Stock Option (Right to buy)	$6.38	07/08/2026		M		32,375		⁽³⁾	02/06/2029	Common Stock	32,375	$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. Following the sales reported in this Form 4, the Reporting Person has a total of 1,564,551 options to purchase shares of common stock that are vested and immediately exercisable and a total of 813,949 options to purchase shares of common stock that have not yet vested.

2. The sale prices ranged from $24.00 to $24.43

3. This option is fully vested.

	/s/ Michael A. Metzger	07/09/2026
	** 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.
* Form 4: SEC 1474 (03-26)

Source: View Original Filing on SEC EDGAR