Statement of Changes in Beneficial Ownership (4)

FORM 4 [ ] Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES
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Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

1. Name and Address of Reporting Person ^* Stein Kevin M	2. Issuer Name and Ticker or Trading Symbol TransDigm Group INC [ TDG ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner __X__ Officer (give title below) _____ Other (specify below) President & CEO
(Last) (First) (Middle) 1301 E. 9TH ST., SUITE 3000	3. Date of Earliest Transaction (MM/DD/YYYY) 2/17/2021
(Street) CLEVELAND, OH 44114 (City) (State) (Zip)	4. If Amendment, Date Original Filed (MM/DD/YYYY)	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. Trans. Date	2A. Deemed Execution Date, if any	3. Trans. 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. Trans. Date	2A. Deemed Execution Date, if any	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	2/17/2021		M		9900	A	$191.79	11247	D
Common Stock	2/17/2021		S		1995	D	$564.9421 ⁽¹⁾	9252	D
Common Stock	2/17/2021		S		1477	D	$566.1036 ⁽²⁾	7775	D
Common Stock	2/17/2021		S		928	D	$597.1903 ⁽³⁾	6847	D
Common Stock	2/17/2021		S		1265	D	$568.6061 ⁽⁴⁾	5582	D
Common Stock	2/17/2021		S		1830	D	$569.6543 ⁽⁵⁾	3752	D
Common Stock	2/17/2021		S		895	D	$570.5545 ⁽⁶⁾	2857	D
Common Stock	2/17/2021		S		600	D	$571.4842 ⁽⁷⁾	2257	D
Common Stock	2/17/2021		S		510	D	$572.4991 ⁽⁸⁾	1747	D
Common Stock	2/17/2021		S		300	D	$573.6633 ⁽⁹⁾	1447	D
Common Stock	2/17/2021		S		100	D	$574.56	1347	D

*Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)*
1. Title of Derivate Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Trans. Date	3A. Deemed Execution Date, if any	4. Trans. 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		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 of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
1. Title of Derivate Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Trans. Date	3A. Deemed Execution Date, if any	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)			11. Nature of Indirect Beneficial Ownership (Instr. 4)
Stock Option	$191.79	2/17/2021		M			9900	9/30/2015	11/13/2024	Common Stock	9900	$0.00	128700	D

Explanation of Responses:
(1)	Price reported constitutes the average weighted price of shares sold. Shares were sold at varying prices in the range of $564.60 - $565.50. The reporting person hereby undertakes, upon request of the Commission, the issuer or a security holder of the issuer, to provide full information regarding the number of shares sold at each separate price.
(2)	Price reported constitutes the average weighted price of shares sold. Shares were sold at varying prices in the range of $565.80 - $566.66. The reporting person hereby undertakes, upon request of the Commission, the issuer or a security holder of the issuer, to provide full information regarding the number of shares sold at each separate price.
(3)	Price reported constitutes the average weighted price of shares sold. Shares were sold at varying prices in the range of $566.81 - $567.72. The reporting person hereby undertakes, upon request of the Commission, the issuer or a security holder of the issuer, to provide full information regarding the number of shares sold at each separate price.
(4)	Price reported constitutes the average weighted price of shares sold. Shares were sold at varying prices in the range of $568.07 - $569.00. The reporting person hereby undertakes, upon request of the Commission, the issuer or a security holder of the issuer, to provide full information regarding the number of shares sold at each separate price.
(5)	Price reported constitutes the average weighted price of shares sold. Shares were sold at varying prices in the range of $569.06 - $567.00. The reporting person hereby undertakes, upon request of the Commission, the issuer or a security holder of the issuer, to provide full information regarding the number of shares sold at each separate price.
(6)	Price reported constitutes the average weighted price of shares sold. Shares were sold at varying prices in the range of $570.09 - $571.00. The reporting person hereby undertakes, upon request of the Commission, the issuer or a security holder of the issuer, to provide full information regarding the number of shares sold at each separate price.
(7)	Price reported constitutes the average weighted price of shares sold. Shares were sold at varying prices in the range of $571.34 - $571.68. The reporting person hereby undertakes, upon request of the Commission, the issuer or a security holder of the issuer, to provide full information regarding the number of shares sold at each separate price.
(8)	Price reported constitutes the average weighted price of shares sold. Shares were sold at varying prices in the range of $572.35 - $573.18. The reporting person hereby undertakes, upon request of the Commission, the issuer or a security holder of the issuer, to provide full information regarding the number of shares sold at each separate price.
(9)	Price reported constitutes the average weighted price of shares sold. Shares were sold at varying prices in the range of $573.39 - $574.22. The reporting person hereby undertakes, upon request of the Commission, the issuer or a security holder of the issuer, to provide full information regarding the number of shares sold at each separate price.

Remarks:
All transactions reported hereunder were made pursuant to an established 10b5-1 plan.

Reporting Owners
Reporting Owner Name / Address	Relationships
Reporting Owner Name / Address	Director	10% Owner	Officer	Other
Stein Kevin M 1301 E. 9TH ST. SUITE 3000 CLEVELAND, OH 44114			President & CEO