Ancestry.com shares, which have lost more than 40 percent over the last six months on fears of the company's new pricing plan hurting sales growth, rose 20 percent on Thursday.

The company, which operates a website that allows people to trace their family roots by scouring online records, said it expects 2012 revenue growth in the mid-to-high teens.

Analysts on average expect the company to grow 2012 revenue by 14.6 percent, according to Thomson Reuters I/B/E/S.

Ancestry.com has been testing prices for its subscriptions and the pricing change now appear to be finalized, Piper Jaffray analysts said in a note to clients.

The company has streamlined the pricing on its subscriptions to include a monthly and six-month options, with the six-month option for about $78.

"We believe the overall changes make for a cleaner page for the user and an easier-to-swallow price point for the longer term package," the analysts said.

Average monthly churn, a measure of customer attrition, for the fourth quarter fell to 3.8 percent from 3.9 percent last year.

The company said it ended the year with 1.7 million paying subscribers, compared with 1.4 million subscribers a year ago.

Shares of the company were up 16 percent at $26.47 in late-morning trade on the Nasdaq. They touched a three-month high of $27.47 earlier in the day.

(Reporting by Saqib Iqbal Ahmed and Supantha Mukherjee in Bangalore; Editing by Maju Samuel)

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