May 15 (Reuters) - TPG Capital’s growth investment arm has raised its stake in Tanium Inc with a $175 million investment, valuing the U.S. cyber security startup at around $5 billion, people familiar with the matter said on Tuesday.

TPG Growth’s new investment boosts Tanium’s valuation ahead of an initial public offering that the company is considering but has not yet decided to launch, the sources said. Tanium’s previously known valuation was $3.75 billion about a year ago.

The deal marks TPG Growth’s third investment in Tanium. The private equity firm will buy the stock of early employees as part of the deal, the sources said. None of the funds will go to the company’s father-and-son founders, David and Orion Hindawi, the sources added. The size of TPG’s stake in the company could not be learned.

Talks are underway for $25 million of additional stock to be sold to existing investors besides TPG, according to the sources. Other investors in Tanium include Andreessen Horowitz, IVP and T. Rowe Price.

The sources asked not to be identified because the matter is confidential. TPG declined to comment, while a representative for Tanium could not be reached for comment.

Founded in 2007, Tanium provides computer system security and management for government agencies and companies, allowing them to scan and assess every device on a network within seconds. Tanium’s customers include 12 of the top 15 U.S. banks and six of the top ten U.S. retailers, as well as the U.S. Department of Defense.

The company suffered from the departures of several senior executives last year, amid media reports on employee complaints about Orion Hindawi’s management style as CEO and allegations by a handful of staff that they were fired just before their options vested.

Hindawi told Reuters last year a board investigation found no systematic employee terminations, and that the company had lost no customers.

Tanium said before its previous funding round that it had $300 million in cash and investments, 100 percent revenue growth and was profitable.

Should Tanium go ahead with its IPO plans, it will be one of the few cyber security companies to attract enough stock market investor confidence to go public, in what has become a fiercely competitive sector. Zscaler Inc, which also counts TPG as an investor, went public in March, and is now trading above its IPO price. Another cyber security company Carbon Black filed for an IPO last month. (Reporting by Liana B. Baker in New York; editing by Diane Craft)