Quintiles, which went private in 2008, has selected three banks to handle a return to the public markets, sources have told Reuters.

The three are: Morgan Stanley, Barclays and JPMorgan & Chase.

The three would handle the initial public offering jointly, Reuters said.

The world’s largest life science services firm has been rumored to be planning a return to the stock market for several months.

Quintiles’ current investors include Bain Capital and TPG Capital.

TPG, Morgan Stanley, Barclays and JPMorgan declined comment when contacted by Reuters.

Quintiles, which is based in Durham, has consistently refused to comment about its financial plans.

The firm reported some $3.5 billion in revenue for 12 months endong June 30 of 2012, according to Moody’s Investors Service.

A report from Bloomberg news earlier this week said Quintiles was interviewing banks for an IPO.

Reuters described the interview process as a “bake-off.”

The company was taken private by co-founder and top executive Dennis Gillings in 2008. Gillings, then the chairman and chief executive officer, cited being free from the scrutiny given public companies, was one of the major reasons for the decision.

Now, Gillings has moved into a far less active role with Tom Pike taking over as CEO last year.

And since then, talk has circulated that Quintiles might go public again.

In recent months, the company set out to refinance its debt and also to raise money to pay its private investors a dividend.

The company is aiming to go public later this year, sources told Bloomberg.

In September, people familiar with the matter said the company may file for the IPO in the next 18 months.

A group of private-equity firms led by TPG and Bain bought Quintiles in 2008 in a deal that valued the company at about $3.8 billion, a person familiar with the matter said last year.

Quintiles is among the contract-research organizations whose revenue growth has picked up as drugmakers outsource trials and testing, Moody’s Investors Service said in a Sept. 12 research note. The company hired new Chief Executive Officer Tom Pike in April and has bought up smaller competitors.

Two of Quintiles’s biggest competitors by sales are inVentiv Health Inc. and Catalent Pharma Solutions Inc., according to Moody’s, and both are closely held by private- equity firms. Blackstone Group LP acquired Catalent from Cardinal Health Inc. in 2007 for $3.3 billion, according to data compiled by Bloomberg. Thomas H. Lee Partners LP bought inVentiv in 2010 for $1.09 billion.

[QUINTILES ARCHIVE: Check out 11 years of Quintiles stories as reported in WRAL Tech Wire.]