July 14 (Reuters) - GoHealth Inc GOCO.O raised $913.5 million in its initial public offering (IPO) on Tuesday, more than quadrupling its valuation in less than a year, amid rapid growth in its U.S. online health insurance marketplace, people familiar with the matter said.

GoHealth priced 43.5 million shares at $21 in its IPO, above its indicated price range of $18 to $20, the sources said. The company was previously looking to sell 39.5 million shares.

This gives GoHealth a valuation of close to $6.6 billion, ten months after private equity firm Centerbridge Partners LP invested in it at a $1.5 billion valuation.

The sources requested anonymity ahead of an official announcement. GoHealth did not immediately respond to a request for comment.

(Reporting by Rebecca Spalding in New York Editing by Chris Reese)

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