TNGX Rule 144 Notice: 363,541 Shares via BTIG; Third Rock Recent Sales

Rhea-AI Filing Summary

Tango Therapeutics, Inc. (TNGX) Form 144 notifies a proposed sale of 363,541 common shares through BTIG, LLC with an aggregate market value of $2,672,026.35, against 111,260,247 shares outstanding. The approximate sale date is 09/16/2025. The filing shows the shares to be sold were acquired in two pre-IPO wire transactions on 03/23/2017 (23,067 shares) and 07/24/2017 (340,474 shares). The notice also discloses multiple recent sales by Third Rock Ventures IV, L.P., totaling 2,131,559 shares across August and September 2025 with gross proceeds reported for each trade. The filer attests there is no undisclosed material adverse information and certifies compliance with the notice requirements.

Positive

• Filing compliance: The Form 144 provides the required details for a Rule 144 notice, including broker, share counts, acquisition dates, and attestation of no undisclosed material adverse information.
• Long-held shares: The shares to be sold were acquired in pre-IPO transactions in 2017, showing they are longstanding holdings rather than recent insider grants.

Negative

• Significant affiliate dispositions: Third Rock Ventures IV, L.P. sold a total of 2,131,559 shares in Aug–Sep 2025 with reported gross proceeds, representing a notable supply of shares into the market.
• Potential dilution of market sentiment: Multiple large sales by an affiliated investor are disclosed, which may be perceived negatively by some market participants even though this is a disclosure rather than an operational event.

Insights

Securities Analyst

TL;DR: A compliance filing reporting a planned sale of 363,541 pre-IPO shares and prior significant dispositions by a major holder.

The Form 144 documents a proposed brokered sale of 363,541 common shares valued at $2.67 million, to be executed via BTIG on 09/16/2025. Acquisition records show these shares originated from pre-IPO wire purchases in 2017, indicating long-held positions. The filing also itemizes large prior sales by Third Rock Ventures IV, L.P. totaling 2,131,559 shares in Aug–Sep 2025 with disclosed gross proceeds. From a securities perspective this is primarily a disclosure/compliance event; it provides transparency into insider and affiliate liquidity but does not contain operational or financial performance data.

Corporate Governance Expert

TL;DR: The notice shows material insider/affiliate selling activity but is presented as a routine Rule 144 disclosure with the required attestation.

The filing fulfills Rule 144 notice obligations by specifying the class, broker, quantity, market value, outstanding shares, acquisition history, and sale timing. The filer affirms no undisclosed material adverse information. The disclosure of multiple prior disposals by Third Rock Ventures IV, L.P. signals substantive liquidity events for a principal holder; governance stakeholders will view this as relevant for share supply and insider alignment but the filing contains no commentary on intent or company operations.

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

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	BTIG, LLC 350 Bush Street 9th Floor San Francisco CA 94104	363541	2672026.35	111260247	09/16/2025	NASDAQ GM

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	03/23/2017	Pre-IPO investment	Tango Therapeutics Inc			23067	03/23/2017	Wire
Common	07/24/2017	Pre-IPO investment	Tango Therapeutics Inc			340474	07/24/2017	Wire

* 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
Third Rock Ventures IV, L.P. 201 BROOKLINE AVENUE Suite 1401 BOSTON MA 02215	Common	08/19/2025	1100000	2115358.00
Third Rock Ventures IV, L.P. 201 BROOKLINE AVENUE Suite 1401 BOSTON MA 02215	Common	08/22/2025	302194	2103270.24
Third Rock Ventures IV, L.P. 201 BROOKLINE AVENUE suite 1401 BOSTON MA 02215	Common	09/05/2025	642906	4500342.00
Third Rock Ventures IV, L.P. 201 BROOKLINE AVENUE Suite 1401 BOSTON MA 02215	Common	09/08/2025	86459	2557620.00

144: Remarks and Signature

Remarks

Date of Notice

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 Tango Therapeutics' (TNGX) Form 144 disclose about the proposed sale?

The Form 144 discloses a proposed sale of 363,541 common shares through BTIG, LLC with aggregate market value of $2,672,026.35 and an approximate sale date of 09/16/2025.

When were the shares to be sold originally acquired?

The shares were acquired in two pre-IPO wire transactions on 03/23/2017 (23,067 shares) and 07/24/2017 (340,474 shares).

Has any related party sold shares recently according to the filing?

Yes. Third Rock Ventures IV, L.P. reported sales of 1,100,000 shares on 08/19/2025, 302,194 on 08/22/2025, 642,906 on 09/05/2025, and 86,459 on 09/08/2025, totaling 2,131,559 shares with listed gross proceeds for each trade.

Who is the broker handling the proposed sale?

The broker named in the filing is BTIG, LLC located at 350 Bush Street, 9th Floor, San Francisco, CA 94104.

How many shares outstanding does the filing report?

The filing reports 111,260,247 shares outstanding for the issuer.