	UNITED STATES
	SECURITIES AND EXCHANGE COMMISSION
	Washington, D.C. 20549

SCHEDULE 13G

Under the Securities Exchange Act of 1934
(Amendment No. 3)*

Volterra Semiconductor Corporation

(Name of Issuer)

Common Stock

(Title of Class of Securities)

928708106

(CUSIP Number)

12/31/09

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

x	Rule 13d-1(b)
o	Rule 13d-1(c)
o	Rule 13d-1(d)

*The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter the disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

CUSIP No. 928708106

	1.	Names of Reporting Persons. I.R.S. Identification Nos. of above persons (entities only) Schroder Investment Management North America Inc. 13-4064414

	2.	Check the Appropriate Box if a Member of a Group (See Instructions)
		(a)		o
		(b)		o

	3.	SEC Use Only

	4.	Citizenship or Place of Organization Delaware

Number of Shares Beneficially Owned by Each Reporting Person With			5.		Sole Voting Power 739,500

			6.		Shared Voting Power 12,400

			7.		Sole Dispositive Power 751,900

			8.		Shared Dispositive Power

	9.	Aggregate Amount Beneficially Owned by Each Reporting Person 751,900

	10.	Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) o

	11.	Percent of Class Represented by Amount in Row (9) 2.981%

	12.	Type of Reporting Person (See Instructions) IA

Item 1.
	(a)	Name of Issuer Volterra Semiconductor Corporation
	(b)	Address of Issuer’s Principal Executive Offices 47467 Freemont Blvd., Freemont, CA 94538

Item 2.
	(a)	Name of Person Filing Schroder Investment Management North America Inc.
	(b)	Address of Principal Business Office or, if none, Residence 875 Third Avenue, 21st Floor New York, NY 10022
	(c)	Citizenship Delaware
	(d)	Title of Class of Securities Common Stock
	(e)	CUSIP Number 928708106

Item 3.	If this statement is filed pursuant to §§240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
	(a)	o	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
	(b)	o	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
	(c)	o	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
	(d)	o	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
	(e)	x	An investment adviser in accordance with §240.13d-1(b)(1)(ii)(E);
	(f)	o	An employee benefit plan or endowment fund in accordance with §240.13d-1(b)(1)(ii)(F);
	(g)	o	A parent holding company or control person in accordance with §240.13d-1(b)(1)(ii)(G);
	(h)	o	A savings association as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
	(i)	o	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
	(j)	o	A non-U.S. institution in accordance with § 240.13d–1(b)(1)(ii)(J);
	(k)	o	Group, in accordance with § 240.13d–1(b)(1)(ii)(K). If filing as a non-U.S. institution in accordance with § 240.13d–1(b)(1)(ii)(J), please specify the type of institution:____________________________

Item 4.	Ownership
Provide the following information regarding the aggregate number and percentage of the class of securities of the issuer identified in Item 1.
	(a)	Amount beneficially owned: 751,900
	(b)	Percent of class: 2.981%
	(c)	Number of shares as to which the person has:
		(i)	Sole power to vote or to direct the vote 739,500
		(ii)	Shared power to vote or to direct the vote 12,400
		(iii)	Sole power to dispose or to direct the disposition of 751,900
		(iv)	Shared power to dispose or to direct the disposition of

Item 5.	Ownership of Five Percent or Less of a Class
If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of more than five percent of the class of securities, check the following x.

Item 6.	Ownership of More than Five Percent on Behalf of Another Person
Not applicable.

Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on By the Parent Holding Company or Control Person
Not applicable.

Item 8.	Identification and Classification of Members of the Group
Original filing included holdings by Schroder Investment Management Ltd “SIM Ltd” on the basis that is under common control with the filer. SIM Ltd holds 12,400 shares.

Item 9.	Notice of Dissolution of Group
Not applicable.

Item 10.

Certification

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect.

Signature

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

	February 12, 2010
	Date
	/s/ Stephen M. DeTore
	Signature
	Stephen M. DeTore Chief Compliance Officer
	Name/Title