[Form 4] TransDigm Group INC Insider Trading Activity

Rhea-AI Filing Summary

Robert J. Small, a director of TransDigm Group Inc. (TDG), reported multiple transactions in the company’s common stock on Form 4. The filing shows indirect holdings of 441,814 shares by Stockbridge Fund, L.P. and 60,246 shares held by family trusts. On 09/12/2025 several sales by Stockbridge Partners LLC are reported at weighted-average prices ranging approximately from $1,270.85 to $1,284.35 across multiple blocks. The filing also discloses a 09/15/2025 gift of 10,000 shares to a donor-advised fund (reported as $0 consideration). The reporting person disclaims direct beneficial ownership of the shares held by the entities named.

Positive

• Full disclosure of multiple sales with weighted-average price ranges is provided, improving transparency
• Entity-level ownership and managerial roles are clearly explained in footnotes
• Charitable gift of 10,000 shares to a donor-advised fund is explicitly reported

Negative

• Multiple sizable sales reported on 09/12/2025 by Stockbridge Partners LLC, which may be viewed unfavorably by some investors
• Reporting person disclaims direct beneficial ownership, making it harder to interpret personal economic exposure from this filing

Insights

Securities Analyst

TL;DR: Director filed multiple indirect sales at high single-share prices and reported entity-level holdings plus a gift of 10,000 shares.

The Form 4 documents a series of block sales executed on 09/12/2025 by Stockbridge Partners LLC at weighted-average prices in a tight band from about $1,270.85 to $1,284.35, reported across many individual transactions. The filing clarifies that the shares are held indirectly by investment entities (Stockbridge Fund, L.P. and Stockbridge Partners LLC) and that the reporting person disclaims direct beneficial ownership except for any pecuniary interest. A separate 09/15/2025 disposition shows a gift of 10,000 shares to a donor-advised fund. For investors, the material facts are transaction dates, price ranges, and the entity-level ownership disclosures.

Corporate Governance Expert

TL;DR: Form 4 shows routine section 16 disclosure of indirect holdings and multiple block sales plus a charitable gift, with standard disclaimers.

The filing contains detailed explanatory footnotes describing the ownership chain and the reporting person’s managerial roles in the entities that hold the shares. The presentation follows typical Section 16 reporting conventions: multiple sales reported with weighted-average prices and an explicit disclaimer of beneficial ownership except for pecuniary interest. The documented gift to a donor-advised fund is reported as a $0 disposition, consistent with charitable transfer disclosure requirements. No derivative positions are reported on this form.

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^*

SMALL ROBERT J

(Last) (First) (Middle)

C/O BERKSHIRE PARTNERS LLC

200 CLARENDON STREET, 35TH FLOOR

(Street)

BOSTON MA 02116

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
TransDigm Group INC [ TDG ]

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)
09/12/2025

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								441,814	I	By Stockbridge Fund, L.P.(1)
Common Stock	09/12/2025		S		403	D	$1,271.3896(4)	88,016	I	By Stockbridge Partners LLC(2)
Common Stock	09/12/2025		S		256	D	$1,272.4503(5)	87,760	I	By Stockbridge Partners LLC(2)
Common Stock	09/12/2025		S		261	D	$1,273.55(6)	87,499	I	By Stockbridge Partners LLC(2)
Common Stock	09/12/2025		S		488	D	$1,274.216(7)	87,011	I	By Stockbridge Partners LLC(2)
Common Stock	09/12/2025		S		597	D	$1,275.2307(8)	86,414	I	By Stockbridge Partners LLC(2)
Common Stock	09/12/2025		S		504	D	$1,276.4083(9)	85,910	I	By Stockbridge Partners LLC(2)
Common Stock	09/12/2025		S		521	D	$1,277.164(10)	85,389	I	By Stockbridge Partners LLC(2)
Common Stock	09/12/2025		S		300	D	$1,278.3236(11)	85,089	I	By Stockbridge Partners LLC(2)
Common Stock	09/12/2025		S		501	D	$1,279.1871(12)	84,588	I	By Stockbridge Partners LLC(2)
Common Stock	09/12/2025		S		287	D	$1,280.5415(13)	84,301	I	By Stockbridge Partners LLC(2)
Common Stock	09/12/2025		S		520	D	$1,281.2204(14)	83,781	I	By Stockbridge Partners LLC(2)
Common Stock	09/12/2025		S		149	D	$1,282.6363(15)	83,632	I	By Stockbridge Partners LLC(2)
Common Stock	09/12/2025		S		197	D	$1,283.1869(16)	83,435	I	By Stockbridge Partners LLC(2)
Common Stock	09/12/2025		S		16	D	$1,284.1729(17)	83,419	I	By Stockbridge Partners LLC(2)
Common Stock								60,246	I	By Family Trusts(3)
Common Stock	09/15/2025		G		10,000	D	$0(18)	5,581	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

Explanation of Responses:

1. Represents shares held by Stockbridge Fund, L.P. ("SF"). Berkshire Partners Holdings LLC ("BPH") is the general partner of BPSP, L.P. ("BPSP"), which is the managing member of SP, the registered investment adviser to SF. Stockbridge Associates LLC ("SA") is the general partner of SF. The Reporting Person is a managing member of each of BPH, BPSP, SP and SA. As such, the Reporting Person may be deemed to share voting and dispositive power with respect to the shares of the Issuer's common stock held by SF. However, the Reporting Person disclaims beneficial ownership of these shares, except to the extent, if any, of his pecuniary interest therein, and the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of the reported securities for purposes of Section 16 or for any other purposes.

2. Represents shares held by Stockbridge Partners LLC ("SP") on behalf of a managed account over which it has shared voting and sole dispositive power. This Form 4 has been filed because the Reporting Person is a director of the Issuer and a managing member of SP. As such, the Reporting Person may be deemed to share voting and dispositive power with respect to the shares of the Issuer's common stock held by SP. However, the Reporting Person disclaims beneficial ownership of these shares, except to the extent, if any, of his pecuniary interest therein, and the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of the reported securities for purposes of Section 16 or for any other purposes.

3. Represents shares of Common Stock beneficially owned by certain family trusts. The Reporting Person's immediate family members are beneficiaries of such family trusts.

4. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions within the range of $1270.8479 to $1271.8478. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

5. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions within the range of $1271.8479 to $1272.8478. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

6. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions within the range of $1272.8479 to $1273.8478. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

7. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions within the range of $1273.8479 to $1274.8478. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

8. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions within the range of $1274.8479 to $1275.8478. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

9. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions within the range of $1275.8479 to $1276.8478. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

10. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions within the range of $1276.8479 to $1277.8478. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

11. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions within the range of $1277.8479 to $1278.8478. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

12. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions within the range of $1278.8479 to $1279.8478. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

13. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions within the range of $1279.8479 to $1280.8478. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

14. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions within the range of $1280.8479 to $1281.8478. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

15. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions within the range of $1281.8479 to $1282.8478. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

16. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions within the range of $1282.8479 to $1283.8478. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

17. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions within the range of $1283.8479 to $1284.3525. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

18. Represents shares of Common Stock that were disposed of by the Reporting Person pursuant to a gift to a donor advised fund for no consideration.

	/s/ Robert J. Small	09/16/2025
	** 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

What did the Form 4 filed for TDG disclose about insider holdings?

The filing shows indirect holdings of 441,814 shares by Stockbridge Fund, L.P. and 60,246 shares by family trusts, as reported by Robert J. Small.

When were the stock sales reported on the TDG Form 4 executed?

Multiple sales were executed on 09/12/2025, with weighted-average prices reported in a range of approximately $1,270.85 to $1,284.35.

Were any gifts or donations disclosed in the TDG Form 4?

Yes. The filing discloses a 09/15/2025 disposition reporting a 10,000-share gift to a donor-advised fund at $0 consideration.

Does Robert J. Small claim direct beneficial ownership of the reported shares?

No. The filing contains disclaimers stating he disclaims beneficial ownership of the shares held by the named entities except to the extent of any pecuniary interest.

Are there any derivative securities reported in this Form 4 for TDG?

No. Table II (derivative securities) contains no reported positions or transactions in this filing.