Yahoo’s purchase of Santa Monica-based Launch comes as it prepares to offer Pressplay, a song-streaming service from Sony and Universal, sometime this summer. Pressplay will compete witha slew of new online music services, including MusicNet, which is being run by the other threemajor music labels, and a retooled Napster.

Launch has 7.4 million registered users and “the broadest array of music and music-relatedcontent available on the Web today,” said Ellen Siminoff, Yahoo’s senior vice president ofentertainment and small business. It has not been determined whether job cuts will be required atLaunch, which has about 180 employees, Siminoff said.

The deal values Launch’s stock at 92 cents per share. The shares soared more than 50 percent onthe news Thursday, rising 31 cents to 89 cents in midday trading on the Nasdaq Stock Market.

Yahoo stock was up more than 4 percent, or 85 cents, at $19.58.