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).

1. Name and Address of Reporting Person* Day Christopher (Last) (First) (Middle) 3101 JAY STREET (Street) SANTA CLARA CA 95054 (City) (State) (Zip)	2. Issuer Name and Ticker or Trading Symbol AMBARELLA INC [ AMBA ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) Director 10% Owner X Officer (give title below) Other (specify below) VP, Marketing
	3. Date of Earliest Transaction (Month/Day/Year) 02/26/2018
	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

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
Restricted Stock Units	(1)	02/26/2018		A		3,758(2)		(2)	(2)	Ordinary Shares	3,758	$0.0	3,758	D

Explanation of Responses:

1. Each restricted stock unit represents a contingent right to receive one share of Ambarella, Inc. Ordinary Shares.

2. On March 28, 2017, reporting person was granted an award of RSUs covering a target of 3,758 ordinary shares (the "Target RSU Number"), subject to satisfaction of predetermined, performance-based vesting criteria that could result in 0% to 150% of the Target RSU Number becoming eligible to vest, subject to certain adjustments as described below. On February 26, 2018, the Company's Board of Directors determined that the performance criteria for the RSUs had been satisfied at a level that resulted in 100% of the Target RSU Number becoming eligible for time-based vesting. Pursuant to the time-based vesting requirements, 100% of this portion of the award is scheduled to vest on March 15, 2020, subject to continued service requirements. In addition, the number of shares subject to the RSUs eligible to vest on March 15, 2020 may be increased or decreased by 25% or may remain the same, based on attainment of specified levels of the Company's total stockholder return.

	By: /s/ Michael Morehead, Attorney in Fact For: Christopher Day	02/28/2018
	** 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).
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