UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the

Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): October 29, 2015

PMC-Sierra, Inc.

(Exact name of registrant as specified in its charter)

1380 Bordeaux Drive

Sunnyvale, CA 94089

(408) 239-8000

(Address of principal executive offices, including zip code)

(408) 239-8000

(Registrant’s telephone number, including area code)

Not Applicable

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

Item 1.01. Entry Into A Material Definitive Agreement

On October 29, 2015, PMC-Sierra, Inc., a Delaware corporation (“PMC”), entered into an Amended and Restated Agreement and Plan of Merger by and among PMC, Skyworks Solutions, Inc. and Amherst Acquisition, Inc. (the “Amended and Restated Merger Agreement”), which amends the Agreement and Plan of Merger by and among PMC, Skyworks Solutions, Inc. and Amherst Acquisition, Inc. dated as of October 5, 2015 (the “Original Merger Agreement”).

The Amended and Restated Merger Agreement (i) increases the merger consideration from $10.50 in cash to $11.60 in cash, without interest and subject to any required withholding for taxes, and (ii) increases the termination fee from $70.0 million to $88.5 million. All other terms of the Original Merger Agreement, which was previously filed by PMC as Exhibit 2.1 to the Current Report on Form 8-K filed with the Securities and Exchange Commission on October 6, 2015, remain substantially the same.

The foregoing description of the Amended and Restated Merger Agreement is only a summary, does not purport to be complete, and is qualified in its entirety by reference to the Amended and Restated Merger Agreement, a copy of which is filed as Exhibit 2.1 hereto and is incorporated herein by reference.

The Amended and Restated Merger Agreement has been included to provide investors and security holders with information regarding its terms. It is not intended to provide any other factual information about PMC, Skyworks Solutions, Inc. or Amherst Acquisition, Inc. or any of their respective subsidiaries or affiliates. The representations, warranties, covenants and agreements contained in the Amended and Restated Merger Agreement, which were made only for purposes of that agreement and as of specific dates, were solely for the benefit of the parties to the Amended and Restated Merger Agreement, may be subject to limitations agreed upon by the contracting parties (including being qualified by confidential disclosures made for the purposes of allocating contractual risk between the parties to the Amended and Restated Merger Agreement instead of establishing these matters as facts) and may be subject to standards of materiality applicable to the contracting parties that differ from those applicable to investors and security holders. Investors and security holders are not third-party beneficiaries under the Amended and Restated Merger Agreement and should not rely on the representations, warranties, covenants and agreements or any descriptions thereof as characterizations of the actual state of facts or condition of PMC, Skyworks Solutions, Inc. or Amherst Acquisition, Inc. or any of their respective subsidiaries or affiliates. Moreover, information concerning the subject matter of the representations and warranties may change after the date of the Amended and Restated Merger Agreement, which subsequent information may or may not be fully reflected in the Company’s public disclosures.

Forward-Looking Statements

Certain statements made herein, including, for example, the expected date of closing of the Merger and the potential benefits of the Merger, are “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1965, Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934. These forward-looking statements reflect the current analysis of existing information and are subject to various risks and uncertainties. As a result, caution must be exercised in relying on forward-looking statements. Due to known and unknown risks, our actual results may differ materially from our expectations or projections.

The following factors, among others, could cause actual results to differ materially from those described in these forward-looking statements: the occurrence of any event, change or other circumstances that could give rise to the termination of the Merger Agreement; the outcome of any legal proceedings that could be instituted against PMC or its directors or Skyworks related to the Merger Agreement; the inability to complete the Merger due to the failure to obtain stockholder approval for the Merger or the failure to satisfy other conditions to completion of the Merger, including the receipt of all regulatory approvals related to the Merger; the failure of Skyworks to obtain the

necessary financing arrangements set forth in the debt commitment letters delivered pursuant to the Merger Agreement; risks that the proposed transaction disrupts current plans and operations and the potential difficulties in employee retention as a result of the Merger; the effects of local and national economic, credit and capital market conditions on the economy in general, and other risks and uncertainties described herein, as well as those risks and uncertainties discussed from time to time in our other reports and other public filings with the Securities and Exchange Commission (the “SEC”), including, but not limited to, those detailed in PMC’s Annual Report on Form 10-K for the year ended December 27, 2014 and our most recent quarterly report filed with the SEC and Skyworks’ Annual Report on Form 10-K for the year ended October 3, 2014 and its most recent quarterly report filed with the SEC. The forward-looking statements contained herein are made only as of the date hereof, and we undertake no obligation to update or revise the forward-looking statements, whether as a result of new information, future events or otherwise.

Important Additional Information to be Filed with the SEC

PMC plans to file with the SEC and mail to our stockholders a proxy statement in connection with the transaction. Additionally, PMC will file other relevant materials with the SEC in connection with the transaction. The proxy statement and other relevant materials will contain important information about PMC, Skyworks the transaction and related matters. Investors and security holders are urged to read the proxy statement and the other relevant materials carefully when they become available before making any voting or investment decision with respect to the proposed Merger because they will contain important information about the Merger and the parties to the Merger.

Investors and security holders will be able to obtain free copies of the proxy statement and relevant other documents filed with the SEC by PMC and Skyworks through the website maintained by the SEC at www.sec.gov.

In addition, investors and security holders will be able to obtain free copies of the proxy statement and the other relevant documents filed with the SEC by PMC from PMC by contacting Joel Achramowicz at (408) 239-8630.

PMC and Skyworks, and their respective directors and executive officers, may be deemed to be participants in the solicitation of proxies in respect of the transactions contemplated by the Merger Agreement. Information regarding PMC’s directors and executive officers is contained in PMC’s Form 10-K for the year ended December 27, 2014 and our proxy statement dated March 20, 2015, which are filed with the SEC. Information regarding Skyworks’ directors and executive officers is contained in Skyworks’ Form 10-K for the year ended October 3, 2014 and its proxy statement dated April 8, 2015. Additional information regarding the participants in the solicitation of proxies in respect of the transactions contemplated by the Merger Agreement and a description of their direct and indirect interests, by security holdings or otherwise, will be contained in the proxy statement and other relevant materials to be filed with the SEC when they become available.

Item 9.01. Financial Statements and Exhibits.

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Exhibit Index