UPDATE 1-Japan's Softbank trumps rivals in cellphone signups

(Adds cumulative numbers, share price moves, background)

TOKYO, Feb 7 (Reuters) - Softbank Corp (9984.T: Quote, Profile, Research, Stock Buzz), Japan's smallest mobile phone carrier, won nearly twice as many new subscribers as its two bigger rivals combined in January, data released by the operators showed on Thursday.

Softbank signed up a net 200,700 additional subscribers, beating its rivals for the ninth straight month, after triggering a price war in a saturated market.

No. 2 player KDDI Corp (9433.T: Quote, Profile, Research, Stock Buzz) added a net 82,700 users while Japan's top mobile phone carrier, NTT DoCoMo Inc (9437.T: Quote, Profile, Research, Stock Buzz), came in last with a net 19,800 new users last month.

Shares of Softbank were up 4.2 percent at 0432 GMT, bolstered by the news and Deutsche's "buy" rating on the stock. KDDI was up 4.9 percent and DoCoMo was up 1.3 percent.

Softbank, which launched new student discounts last week, has been pursuing a cut-price strategy to grab users from its bigger rivals, who together control more than 80 percent of the market.

Since buying Vodafone Group Plc's (VOD.L: Quote, Profile, Research, Stock Buzz) Japan mobile unit in 2006, Softbank has pursued market share at the expense of revenues per user, but its market share has budged up only incrementally.

At the end of January, DoCoMo had 53.1 million users, KDDI had 29.6 million and Softbank had 17.8 million. (Reporting by Mayumi Negishi)