Sec Form 4 Filing - Chang Mike F @ ALPHA & OMEGA SEMICONDUCTOR Ltd - 2022-03-15

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 Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Chang Mike F 2. Issuer Name and Ticker or Trading Symbol ALPHA & OMEGA SEMICONDUCTOR Ltd [ AOSL] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director X __ 10% Owner X __ Officer (give title below) _____ Other (specify below) Chief Executive Officer (Last) (First) (Middle) 475 OAKMEAD PARKWAY 3. Date of Earliest Transaction (MM/DD/YY) 03/15/2022 (Street) SUNNYVALE, CA94085 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 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 Shares 03/15/2022 A 70,000( 1 ) A $ 0 4,353,826( 2 ) D Common Shares 03/15/2022 F 29,208( 3 ) D $ 48.65 4,324,618( 2 ) D Common Shares 03/15/2022 F 24,908( 4 ) D $ 48.65 4,299,710( 2 ) D Common Shares 03/15/2022 A 22,500( 5 ) A $ 0 4,322,210( 2 ) D Common Shares 03/15/2022 A 70,000( 6 ) A $ 0 4,392,210( 2 )( 7 ) D Common Shares 03/17/2022 M 56,400 A $ 9.9 4,448,610( 2 )( 7 ) D Common Shares 03/17/2022 S 56,400( 8 ) D $ 55( 9 ) 4,392,210( 2 )( 7 ) 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 (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 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 (MM/DD/YY) 7. Title and Amount of Underlying Securities (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) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Employee Share Option (right to buy) $ 9.9 03/17/2022 M 56,400 ( 10 ) 04/25/2022 Common Share 56,400 $ 0 0 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Chang Mike F 475 OAKMEAD PARKWAY SUNNYVALE, CA94085 X X Chief Executive Officer Signatures /s/ Yanbing Hong, attorney-in-fact for Mike F. Chang 03/17/2022 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The RSU shall vest in equal annual installments over four (4) years from March 15, 2022, provided that the Reporting Person remains in the Issuer's service through each such vesting date. ( 2 )Includes an aggregate of 170,000 shares subject to Restricted Share Unit awards (RSU) granted on March 15, 2019, March 16, 2020, March 15, 2021, and March 15, 2022 which will be issued as such units vest in accordance with their terms, and excludes 70,000 unvested common shares subject to the PSU granted on March 15, 2022, which may become vested upon achievement of certain corporate performance goals in the future. ( 3 )Shares withheld to satisfy the Issuer's tax withholding obligation upon the vesting of restricted share units (RSU) granted on March 15, 2018, March 15, 2019, March 16, 2020, and March 15, 2021. ( 4 )Shares withheld to satisfy the Issuer's tax withholding obligation upon the vesting of Performance Share Units (PSU) granted on March 15, 2018, March 16, 2020, and March 15, 2021. ( 5 )Represents the issuance of common shares upon vesting of one-fourth (1/4) of PSU granted on March 15, 2018. The achievement of specified performance goals for such PSU was certified previously by the Compensation Committee on February 27, 2019, and the issuance common shares thereunder are subject to additional service-based vesting conditions in four equal annual installment commencing in March 2019. ( 6 )Represents the vesting of PSU granted on March 15, 2021 upon the achievement of specified performance goals as certified previously by the Compensation Committee on February 24, 2022 and the issuance of shares thereunder is subject to vesting in four equal annual installment commencing in March 2022 provided that the Reporting Person remains in the issuer's service through each such vesting date. ( 7 )Includes 52,500 unvested shares subject to the PSU granted on March 15, 2021 which are subject to vesting upon satisfaction of service-based vesting conditions by the Reporting Person. ( 8 )The sales were effected pursuant to a Rule 10b5-1 trading plan adopted previously by the Reporting Person. ( 9 )The price reported in Column 4 is the exact price at which all shares were sold. ( 10 )All options are fully vested and exercisable.

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