[144] Syndax Pharmaceuticals, Inc. SEC Filing

Rhea-AI Filing Summary

Syndax Pharmaceuticals (SNDX) reported a Notice of Proposed Sale on Form 144 indicating an intended sale of 157,307 common shares through Morgan Stanley Smith Barney (NASDAQ) with an aggregate market value of $2,680,511.28, and an approximate sale date of 09/08/2025. The shares were acquired on 09/08/2025 by exercise of stock options from the issuer, with payment in cash. The filing also discloses a prior sale by Michael Metzger of 7,534 shares on 07/16/2025 for $69,953.19. The filer certifies no undisclosed material adverse information.

Positive

• Transparent disclosure of broker, share count, aggregate market value, and proposed sale date complying with Rule 144 reporting requirements
• Acquisition method specified as exercise of stock options with cash payment, clarifying the origin of the shares

Negative

• Notable proposed sale size of 157,307 shares valued at $2,680,511.28, which may increase available float on or after 09/08/2025
• Recent insider selling already occurred: 7,534 shares sold on 07/16/2025 for $69,953.19

Insights

Securities/Corporate Governance Analyst

TL;DR: Insider intends to sell 157,307 shares (about $2.68M) acquired by option exercise; prior small sale also disclosed.

The Form 144 notifies the market of a proposed sale by an insider or affiliate, specifying the broker, share count, and dollar value. The shares were acquired by exercise of stock options on the same date listed for sale, with cash payment. For investors, this is a disclosure of potentially dilutive insider-originated supply entering the market on 09/08/2025. The prior July 16, 2025 sale of 7,534 shares for $69,953.19 by Michael Metzger is also reported. The filing contains required certifications and no statement of undisclosed material information.

Securities Transactions Specialist

TL;DR: Transaction logistics are clear: brokered sale via Morgan Stanley, option exercise, cash payment, and proper Form 144 disclosure.

The submission details execution mechanics: broker name and address, class of security, shares outstanding used to calculate proportions, and payment method. The acquisition column lists the shares as obtained by option exercise on the same date as the proposed sale, which is relevant for Rule 144 timing and settlement considerations. The filing meets standard disclosure elements for an intended sale under Rule 144.

Form 144 Filer Information	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form 144 NOTICE OF PROPOSED SALE OF SECURITIES PURSUANT TO RULE 144 UNDER THE SECURITIES ACT OF 1933
FORM 144

144: Filer Information

Filer CIK
Filer CCC
Is this a LIVE or TEST Filing?	LIVE TEST
Submission Contact Information
Name
Phone
E-Mail Address

144: Issuer Information

Name of Issuer

SEC File Number

Address of Issuer

Phone

Name of Person for Whose Account the Securities are To Be Sold

See the definition of "person" in paragraph (a) of Rule 144. Information is to be given not only as to the person for whose account the securities are to be sold but also as to all other persons included in that definition. In addition, information shall be given as to sales by all persons whose sales are required by paragraph (e) of Rule 144 to be aggregated with sales for the account of the person filing this notice.

Relationship to Issuer

Relationship to Issuer

144: Securities Information

Title of the Class of Securities To Be Sold	Name and Address of the Broker	Number of Shares or Other Units To Be Sold	Aggregate Market Value	Number of Shares or Other Units Outstanding	Approximate Date of Sale	Name the Securities Exchange
Common	Morgan Stanley Smith Barney LLC Executive Financial Services 1 New York Plaza 8th Floor New York NY 10004	157307	2680511.28	86141862	09/08/2025	NASDAQ

Furnish the following information with respect to the acquisition of the securities to be sold and with respect to the payment of all or any part of the purchase price or other consideration therefor:

144: Securities To Be Sold

Title of the Class	Date you Acquired	Nature of Acquisition Transaction	Name of Person from Whom Acquired	Is this a Gift?	Date Donor Acquired	Amount of Securities Acquired	Date of Payment	Nature of Payment *
Common	09/08/2025	Exercise of Stock Options	Issuer			157307	09/08/2025	Cash

* If the securities were purchased and full payment therefor was not made in cash at the time of purchase, explain in the table or in a note thereto the nature of the consideration given. If the consideration consisted of any note or other obligation, or if payment was made in installments describe the arrangement and state when the note or other obligation was discharged in full or the last installment paid.

Furnish the following information as to all securities of the issuer sold during the past 3 months by the person for whose account the securities are to be sold.

144: Securities Sold During The Past 3 Months

Name and Address of Seller	Title of Securities Sold	Date of Sale	Amount of Securities Sold	Gross Proceeds
MICHAEL METZGER 730 Third Avenue, 9th Floor New York NY 10017	Common	07/16/2025	7534	69953.19

144: Remarks and Signature

Remarks

Date of Notice

Date of Plan Adoption or Giving of Instruction, If Relying on Rule 10b5-1

ATTENTION:

The person for whose account the securities to which this notice relates are to be sold hereby represents by signing this notice that he does not know any material adverse information in regard to the current and prospective operations of the Issuer of the securities to be sold which has not been publicly disclosed. If such person has adopted a written trading plan or given trading instructions to satisfy Rule 10b5-1 under the Exchange Act, by signing the form and indicating the date that the plan was adopted or the instruction given, that person makes such representation as of the plan adoption or instruction date.

Signature

ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)

FAQ

What does Syndax Pharmaceuticals' Form 144 filed for SNDX disclose?

The filing discloses a proposed sale of 157,307 common shares valued at $2,680,511.28 through Morgan Stanley, with an approximate sale date of 09/08/2025.

How were the 157,307 shares acquired according to the Form 144?

The shares were acquired on 09/08/2025 by exercise of stock options from the issuer, with cash used for payment.

Who is the broker handling the proposed sale?

The broker named is Morgan Stanley Smith Barney LLC Executive Financial Services located at 1 New York Plaza, 8th Floor, New York, NY 10004.

Did the filer sell any shares recently prior to this Form 144?

Yes. The filing reports Michael Metzger sold 7,534 shares on 07/16/2025 for $69,953.19.

Does the filing state whether there is any undisclosed material information?

The filer represents by signature that they do not know any material adverse information about the issuer that has not been publicly disclosed.