- Amended Annual Report (10-K/A)

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K/A

(Amendment No. 1)

Mark One)

x	ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the fiscal year ended December 31, 2011

¨	TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from to

Commission file number 000-13059

(Exact name of registrant as specified in its charter)

Delaware	33-0055414
(State or other jurisdiction of Incorporation or organization)	(I.R.S. Employer Identification No.)
3169 Red Hill Avenue, Costa Mesa, California	92626
(Address of principal executive offices)	(Zip Code)

(714) 549-0421

(Registrant’s telephone number, including area code)

Securities registered pursuant to Section 12(b) of the Act:
Title of Each Class:	Name of Each Exchange on Which Registered:
Common Stock, par value $0.01 per share	The NASDAQ Stock Market LLC

Securities registered pursuant to Section 12(g) of the Act: None

Indicate by check mark whether the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act of 1933. YES x NO ¨

Indicate by check mark whether the registrant is not required to file reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934. YES ¨ NO x

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports); and (2) has been subject to such filing requirements for the past 90 days. YES x NO ¨

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files). Yes x No ¨

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K is not contained herein, and will not be contained, to the best of registrant’s knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K. ¨

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See the definitions of “large accelerated filer”, “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act. (Check one):

Large accelerated filer x

Accelerated filer ¨

Non-accelerated filer ¨

Smaller reporting company ¨

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes ¨ No x

The aggregate market value of registrant’s common stock held by non-affiliates as of June 30, 2011 (the last business day of registrant’s most recently completed second fiscal quarter) was approximately $910.1 million.

As of February 5, 2012, there were 24,194,539 shares of registrant’s Common Stock outstanding.

DOCUMENTS INCORPORATED BY REFERENCE: Portions of registrant’s definitive proxy statement for its annual meeting of stockholders to be held on May 16, 2012 are incorporated by reference into Part III of this Form 10-K.

EXPLANATORY NOTE

Ceradyne, Inc. (the “Company”) is filing this Amendment No. 1 to its Form 10-K for the year ended December 31, 2011 (the “Report”) for the purpose of including Interactive Data Files (Exhibit 101) formatted in XBRL (Extensible Business Reporting Language) with detail tagging of the notes to the consolidated financial statements. Previously, the Company included in the Report Interactive Data Files formatted in XBRL with the notes to the consolidated financial statement in block-tagged form. We have also unchecked the box on the cover page regarding disclosure of delinquent filers pursuant to Item 405 of Regulation S-K, as the disclosure of one delinquent filing was included in our definitive proxy statement for our annual meeting of stockholders to be held on May 16, 2012, which proxy statement is incorporated by reference into Part III of the Report. No revisions have been made with respect to any other disclosures contained in the Report.

SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the registrant has duly caused this Amendment to be signed on its behalf by the undersigned, thereunto duly authorized.

April 23, 2012	CERADYNE, INC.

	By:	/s/ J ERROLD J. P ELLIZZON
		Jerrold J. Pellizzon
		Chief Financial Officer

INDEX TO EXHIBITS

Exhibit Number		Description

101.CAL		XBRL Taxonomy Extension Calculation Linkbase.
101.DEF		XBRL Taxonomy Extension Definition Linkbase.
101.INS		XBRL Instance Document.
101.LAB		XBRL Taxonomy Extension Label Linkbase.
101.PRE		XBRL Taxonomy Extension Presentation Linkbase.
101.SCH		XBRL Taxonomy Extension Schema Linkbase.