By Liana B. Baker and Greg Roumeliotis

(Reuters) - F5 Networks Inc <FFIV.O>, a U.S. computer networking company whose technology helps speed up data center traffic, has hired investment bank Goldman Sachs Group Inc <GS.N> following takeover approaches, people familiar with the matter said.

The approaches come as F5 seeks to roll out products with new security features and revitalize its growth, as smaller rivals that take advantage of advances in cloud computing make the networking services market ever more competitive.

F5 is working with Goldman Sachs to field expressions of interest in an acquisition and decide on its next steps, the people said this week, without identifying the parties that approached the company.

F5 has attracted takeover interest in previous years, and there is no certainty that the latest approaches will lead to any deal, the people cautioned.

The sources asked not to be identified because the deliberations are confidential. F5 and Goldman Sachs declined to comment. F5 shares ended trading on Tuesday in New York up 12.6 percent at $123.94 on the news, giving the company a market capitalization of $8.3 billion.

Based in Seattle, Washington, F5 develops products aimed at boosting the security, performance and availability of data centers, applications and servers.

F5 has been seeking to reassure investors over unexpected changes in its top management in recent months. At the end of last year, its newly appointed chief executive officer of six months, Manny Rivelo, resigned because of personal conduct matters.

Rivelo was replaced by John McAdam, a longtime F5 executive and former CEO, who came out of retirement to take over as president and CEO while the company underwent a formal search for a new chief executive.

That search is no longer underway and McAdam said at an investor conference in March that he was "back for good."

Reuters reported in 2010 that F5 Networks had previously attracted interest from companies that included IBM Corp <IBM.N>, Oracle Corp <ORCL.N> and Juniper Networks <JNPR.N>.

On its second-quarter earnings call, F5 said it was experiencing a decline in bookings because of softness in the financial and telecommunications carrier markets, which represent a major source of business for the company.

(Reporting by Liana B. Baker in San Francisco and Greg Roumeliotis in New York; Editing by Richard Chang and Chris Reese)