As filed with the Securities and Exchange Commission on January 31, 2019

Registration No. 333-

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM S-4

REGISTRATION STATEMENT

UNDER THE SECURITIES ACT OF 1933

KLA-Tencor Corporation

(Exact name of Registrant as specified in its charter)

One Technology Drive

Milpitas, California 95305

(408) 875-3000

(Address, including zip code, and telephone number, including area code, of Registrant’s principal executive offices)

Teri A. Little

Executive Vice President and Chief Legal Officer

KLA-Tencor Corporation

One Technology Drive

Milpitas, California 95305

(408) 875-3000

(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copies to:

Approximate date of commencement of proposed sale of the securities to the public: As soon as practicable after this Registration Statement becomes effective and upon completion of the merger described in the enclosed proxy statement/prospectus.

If the securities being registered on this Form are being offered in connection with the formation of a holding company and there is compliance with General Instruction G, check the following box.  ☐

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  ☒ Registration No. 333-224982

If this Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  ☐

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

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act.  ☐

If applicable, place an X in the box to designate the appropriate rule provision relied upon in conducting this transaction:

☐  Exchange Act Rule 13e-4(i) (Cross-Border Issuer Tender Offer)

☐  Exchange Act Rule 14d-1(d) (Cross-Border Third-Party Tender Offer)

CALCULATION OF REGISTRATION FEE

This registration statement will become effective automatically upon filing with the Commission pursuant to Rule 462(b) under the Securities Act of 1933, as amended.

EXPLANATORY NOTE

Pursuant to its Registration Statement on Form S-4 (Registration No. 333-224982) (the “Prior Registration Statement”), declared effective as of June 7, 2018, and as amended to date, KLA-Tencor Corporation (the “Registrant”) registered an aggregate of 12,298,994 shares of its common stock and paid an aggregate fee of $134,258. The Registrant is filing this Registration Statement on Form S-4 pursuant to General Instruction K to Form S-4 and Rule 462(b) of the Securities Act of 1933, as amended, solely to register 30,000 additional shares of its common stock for issuance in connection with the consummation of the merger contemplated by the Agreement and Plan of Merger dated as of March 18, 2018, by and among the Registrant, Orbotech Ltd., a company organized under the Laws of the State of Israel and Tiburon Merger Sub Technologies Ltd, a company organized under the Laws of the State of Israel and an indirect wholly owned subsidiary of the Registrant, as amended May 11, 2018. In connection with the registration of additional shares of its common stock, the Registrant is paying an additional registration fee of $307.

STATEMENT OF INCORPORATION BY REFERENCE

This Registration Statement incorporates by reference the contents of the Prior Registration Statement, including all amendments, supplements and exhibits thereto and all information incorporated or deemed to be incorporated by reference therein. Additional opinions and consents to be filed with this Registration Statement are listed on the Exhibit Index included with this Registration Statement.

Exhibit Index

SIGNATURES

Pursuant to the requirements of the Securities Act, the registrant has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Milpitas, State of California, on January 31, 2019.

Pursuant to the requirements of the Securities Act of 1933, this registration statement has been signed by the following persons in the capacities and on the dates indicated.