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 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 * Pacven Walden Management V Co. Ltd.   2. Issuer Name and Ticker or Trading Symbol AMBARELLA INC [AMBA] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director __X__ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) ONE CALIFORNIA STREET, SUITE 2800 3. Date of Earliest Transaction (Month/Day/Year) 10/15/2012 (Street) SAN FRANCISCO, CA 94111 4. If Amendment, Date Original Filed(Month/Day/Year) 6. Individual or Joint/Group Filing(Check Applicable Line) ___ Form filed by One Reporting Person _X_ 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 (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 Ordinary Shares 10/15/2012   C   2,820,041 A (2) (3) (4) 2,820,041 I By Pacven Walden Ventures V, L.P. (1) Ordinary Shares 10/15/2012   C   9,784 A (2) (3) (4) 9,784 I By Pacven Walden Ventures V Associates Fund, L.P. (1) Ordinary Shares 10/15/2012   C   64,885 A (2) (3) (4) 64,885 I By Pacven Walden Ventures Parallel V-A C.V. (1) Ordinary Shares 10/15/2012   C   64,885 A (2) (3) (4) 64,885 I By Pacven Walden Ventures Parallel V-B C.V. (1) Ordinary Shares 10/15/2012   C   53,148 A (2) (3) (4) 53,148 I By Pacven Walden Ventures V-QP Associates Fund, L.P. (1)

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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 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
Series A Convertible Preference Shares	(2)	10/15/2012		C			1,560,060	(2)	(2)	Ordinary Shares	1,560,060	$ 0	0	I	By Pacven Walden Ventures V, L.P. (1)
Series A Convertible Preference Shares	(2)	10/15/2012		C			5,413	(2)	(2)	Ordinary Shares	5,413	$ 0	0	I	By Pacven Walden Ventures V Associates Fund, L.P. (1)
Series A Convertible Preference Shares	(2)	10/15/2012		C			35,895	(2)	(2)	Ordinary Shares	35,895	$ 0	0	I	By Pacven Walden Ventures Parallel V-A C.V. (1)
Series A Convertible Preference Shares	(2)	10/15/2012		C			35,895	(2)	(2)	Ordinary Shares	35,895	$ 0	0	I	By Pacven Walden Ventures Parallel V-B C.V. (1)
Series A Convertible Preference Shares	(2)	10/15/2012		C			29,402	(2)	(2)	Ordinary Shares	29,402	$ 0	0	I	By Pacven Walden Ventures V-QP Associates Fund, L.P. (1)
Series B Convertible Preference Shares	(3)	10/15/2012		C			653,291	(3)	(3)	Ordinary Shares	653,291	$ 0	0	I	By Pacven Walden Ventures V, L.P. (1)
Series B Convertible Preference Shares	(3)	10/15/2012		C			2,266	(3)	(3)	Ordinary Shares	2,266	$ 0	0	I	By Pacven Walden Ventures V Associates Fund, L.P. (1)
Series B Convertible Preference Shares	(3)	10/15/2012		C			15,031	(3)	(3)	Ordinary Shares	15,031	$ 0	0	I	By Pacven Walden Ventures Parallel V-A C.V. (1)
Series B Convertible Preference Shares	(3)	10/15/2012		C			15,031	(3)	(3)	Ordinary Shares	15,031	$ 0	0	I	By Pacven Walden Ventures Parallel V-B C.V. (1)
Series B Convertible Preference Shares	(3)	10/15/2012		C			12,312	(3)	(3)	Ordinary Shares	12,312	$ 0	0	I	By Pacven Walden Ventures V-QP Associates Fund, L.P. (1)
Series C Convertible Preference Shares	(4)	10/15/2012		C			606,690	(4)	(4)	Ordinary Shares	606,690	$ 0	0	I	By Pacven Walden Ventures V, L.P. (1)
Series C Convertible Preference Shares	(4)	10/15/2012		C			2,105	(4)	(4)	Ordinary Shares	2,105	$ 0	0	I	By Pacven Walden Ventures V Associates Fund, L.P. (1)
Series C Convertible Preference Shares	(4)	10/15/2012		C			13,959	(4)	(4)	Ordinary Shares	13,959	$ 0	0	I	By Pacven Walden Ventures Parallel V-A C.V. (1)
Series C Convertible Preference Shares	(4)	10/15/2012		C			13,959	(4)	(4)	Ordinary Shares	13,959	$ 0	0	I	By Pacven Walden Ventures Parallel V-B C.V. (1)
Series C Convertible Preference Shares	(4)	10/15/2012		C			11,434	(4)	(4)	Ordinary Shares	11,434	$ 0	0	I	By Pacven Walden Ventures V-QP Associates Fund, L.P. (1)

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Pacven Walden Management V Co. Ltd. ONE CALIFORNIA STREET SUITE 2800 SAN FRANCISCO, CA 94111		X
PACVEN WALDEN VENTURES V LP ONE CALIFORNIA STREET SUITE 2800 SAN FRANCISCO, CA 94111		X
Pacven Walden Ventures Parallel V-A C.V. ONE CALIFORNIA STREET SUITE 2800 SAN FRANCISCO, CA 94111		X
Pacven Walden Ventures Parallel V-B C.V. ONE CALIFORNIA STREET SUITE 2800 SAN FRANCISCO, CA 94111		X
PACVEN WALDEN VENTURES V ASSOCIATES FUND LP ONE CALIFORNIA STREET SUITE 2800 SAN FRANCISCO, CA 94111		X
PACVEN WALDEN VENTURES V QP ASSOCIATES FUND LP ONE CALIFORNIA STREET SUITE 2800 SAN FRANCISCO, CA 94111		X

Signatures

/s/ Lip-Bu Tan, as director of Pacven Walden Management V Co. Ltd.		10/15/2012
**Signature of Reporting Person		Date
/s/ Lip-Bu Tan, as director of Pacven Walden Management V Co. Ltd., the general partner of Pacven Walden Ventures V, L.P.		10/15/2012
**Signature of Reporting Person		Date
/s/ Lip-Bu Tan, as director of Pacven Walden Management V Co. Ltd., the general partner of Pacven Walden Ventures Parallel V-A C.V.		10/15/2012
**Signature of Reporting Person		Date
/s/ Lip-Bu Tan, as director of Pacven Walden Management V Co. Ltd., the general partner of Pacven Walden Ventures Parallel V-B C.V.		10/15/2012
**Signature of Reporting Person		Date
/s/ Lip-Bu Tan, as director of Pacven Walden Management V Co. Ltd., the general partner of Pacven Walden Ventures V Associates Fund, L.P.		10/15/2012
**Signature of Reporting Person		Date
/s/ Lip-Bu Tan, as director of Pacven Walden Management V Co. Ltd., the general partner of Pacven Walden Ventures V-QP Associates Fund, L.P.		10/15/2012
**Signature of Reporting Person		Date
/s/ Lip-Bu Tan		10/15/2012
**Signature of Reporting Person		Date
/s/ Andrew Kau		10/15/2012
**Signature of Reporting Person		Date
/s/ Hock Voon Loo		10/15/2012
**Signature of Reporting Person		Date
/s/ Brian Chiang		10/15/2012
**Signature of Reporting Person		Date

Explanation of Responses:

*	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).
(1)	Pacven Walden Management V Co. Ltd. ("Pacven V Mgmnt"), the Designated Filer, is the general partner of Pacven Walden Ventures V, L.P. ("Pacven Ventures V"), Pacven Walden Ventures Parallel V-A, C.V. ("Pacven V Parallel A"), Pacven Walden Ventures Parallel Fund V-B, C.V. ("Pacven V Parallel B"), Pacven Walden Ventures V Associates Fund, L.P. ("Pacven V A") and Pacven Walden Ventures V-QP Associates Fund, L.P. ("Pacven V-QP"). Lip-Bu Tan is the sole director of Pacven V Mgmnt and shares voting and investment power with respect to the shares held by Pacven Ventures V, Pacven V Parallel A, Pacven V Parallel B, Pacven V A and Pacven V-QP with the other members of the Investment Committee of Pacven V Mgmnt. The members of such Investment Committee are Lip-Bu Tan, Andrew Kau, Hock Voon Loo and Brian Chiang. Each member disclaims beneficial ownership of the shares except the extent of his or her pecuniary interest.
(2)	The Series A Convertible Preference Shares converted into Ordinary Shares on a 1-to-1 basis and had no expiration date.
(3)	The Series B Convertible Preference Shares converted into Ordinary Shares on a 1-to-1 basis and had no expiration date.
(4)	The Series C Convertible Preference Shares converted into Ordinary Shares on a 1-to-1 basis and had no expiration date.

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