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):

August 15, 2012

LIMELIGHT NETWORKS, INC.

(Exact name of Registrant as specified in its charter)

222 South Mill Avenue, 8^th Floor

Tempe, AZ 85281

(Address, including zip code, of principal executive offices)

(602) 850-5000

(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):

Limelight Networks, Inc. (the “Company”) is filing this Current Report on Form 8-K to correct an inadvertent administrative error made in a risk factor disclosure contained in the Company’s Quarterly Report on Form 10-Q for the period ended June 30, 2012 filed with the SEC on August 7, 2012. In the risk factor appearing on page 49 of the Form 10-Q, the number of Sales and Marketing employees employed by the Company as of June 30, 2012 was disclosed as 176. The actual number of Sales and Marketing employees at June 30, 2012 was 200. The risk factor below reflects the corrected risk factor. Except as described in the foregoing, no other changes have been made to the risk factors as previously disclosed.

Failure to effectively expand our sales and marketing capabilities could harm our ability to increase our customer base and achieve broader market acceptance of our services.

Increasing our customer base and achieving broader market acceptance of our services will depend to a significant extent on our ability to expand our sales and marketing operations. Historically, we have concentrated our sales force at our headquarters in Tempe, Arizona. However, we are also building a field sales force to augment our sales efforts and to bring our sales personnel closer to our current and potential customers. Developing such a field sales force has been and will continue to be expensive and we have limited knowledge in developing and operating a widely dispersed sales force. As a result, we may not be successful in developing an effective sales force, which could cause our results of operations to suffer.

We believe that there is significant competition for both inside and direct sales personnel with the sales skills and technical knowledge that we require. Our ability to achieve significant growth in revenue in the future will depend, in large part, on our success in recruiting, training and retaining sufficient numbers of inside and direct sales personnel. We have expanded our sales and marketing personnel from a total of 13 at December 31, 2004 to 168 at December 31, 2011. As of June 30, 2012, we had 200 sales and marketing personnel. New hires require significant training and, in most cases, take a significant period of time before they achieve full productivity. Our recent hires and planned hires may not become as productive as we would like, and we may be unable to hire or retain sufficient numbers of qualified individuals in the future in the markets where we do business. Our business will be seriously harmed if these expansion efforts do not generate a corresponding significant increase in revenue.

SIGNATURES

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.