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 21, 2013

SYMMETRICOM, INC.

(Exact name of Registrant as Specified in its Charter)

2300 Orchard Parkway

San Jose, California 95131-1017

(Address of Principal Executive Offices)

(408) 433-0910

(Registrant’s telephone number, including area code)

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 (see General Instruction A.2. below):

Item 2.02. Results of Operations and Financial Condition.

On October 21, 2013, Symmetricom, Inc. (the “Company”) issued a press release, which sets forth certain preliminary financial results for the quarter ended September 29, 2013. A copy of the press release is attached hereto as Exhibit 99.1 and is incorporated herein by reference. Such information shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, and is not incorporated by reference into any filing of the Company, whether made before or after the date hereof, regardless of any general incorporation language in such filing.

Item 9.01. Financial Statements and Exhibits.

(d) Exhibits.

Forward-Looking Statements

This Current Report on Form 8-K contains forward-looking information within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended, and is subject to the safe harbor created by those sections. These forward-looking statements include statements concerning estimates of second quarter fiscal 2014 guidance and future performance and growth as well as the information regarding the usefulness of the non-GAAP financial information. The statements in this Current Report on Form 8-K are made as of the date of this filing, even if subsequently made available by Symmetricom on its website or otherwise. Symmetricom expressly disclaims any obligation to update or revise any forward-looking statement contained herein, whether as a result of a change in its expectations, a change in any events, conditions or circumstances on which a forward-looking statement is based, or otherwise. Symmetricom’s actual results could differ materially from those projected or suggested in these forward-looking statements. Factors that could cause future actual results to differ materially from the results projected in or suggested by such forward-looking statements include, but are not limited to, the risk that the costs associated with the restructuring plan exceeds current estimates or that the Company is unable to recognize anticipated cost savings associated with the plan, the extent and magnitude of customer orders received and shipped within the same quarter, risks relating to general economic conditions in the markets we address and the telecommunications and government markets in general, risks related to the development of our new products and services, reliance on our contract manufacturer, the effects of increasing competition and competitive pricing pressure, uncertainties associated with changing intellectual property laws or misappropriation of intellectual property, developments in and expenses related to litigation, the inability to obtain sufficient amounts of key components, the rescheduling or cancellation of key customer orders, the loss of a key customer, the effects of new and emerging technologies, the risk that excess inventory may result in write-offs, price erosion and decreased demand, fluctuations in the rate of exchange of foreign currency, changes in our effective tax rate, market acceptance of our new products and services, technological advancements, undetected errors, design flaws, defects in our products or start-up manufacturing difficulties, the risks associated with our international sales, potential short-term investment losses and other risks due to credit market dislocation, geopolitical risks and risk of terrorist activities, the risks associated with attempting to integrate other companies and businesses we acquire, and the risk factors listed from time to time in Symmetricom’s reports filed with the Securities and Exchange Commission, including the annual report on Form 10-K for the fiscal year ended June 30, 2013 and subsequent Forms 10-Q and 8-K.

SIGNATURES

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

EXHIBIT INDEX