Inc reported a 22 percent jump in subscribers in 2011 and a marginal fall in fourth-quarter churn, sending its shares up as much as 20 percent.

The company, which operates a website that allows people to trace their family roots by scouring online records, ended the year with 1.7 million paying subscribers, compared with 1.4 million subscribers a year ago.

Average monthly churn, a measure of customer attrition, for the fourth quarter fell to 3.8 percent from 3.9 percent last year. also said it expects 2012 revenue growth in the mid-to-high teens.

Analysts were expecting revenue of $457.4 million, according to Thomson Reuters I/B/E/S.

Shares of the company were up 17 percent at $26.80 in morning trade on Thursday on the Nasdaq. They touched a three-month high of $27.47 earlier in the session.

(Reporting by Supantha Mukherjee in Bangalore; Editing by Maju Samuel)