Sirius Satellite Radio Inc. (SIRI) and XM Satellite Radio Holdings Inc. (XMSR), the two big players in the emerging satellite radio business, both announced gains in subscribers Monday as 2004 drew to a close.

Washington, D.C.-based XM, the larger of the two, said it had recently surpassed 3.1 million subscribers, having started out the year with 1.3 million. Sirius, which is based in New York, said it had passed the 1 million mark, having started out 2004 with about 260,000.

Competition between the two companies has been heating up fiercely over the past year, with each one signing contracts for hundreds of millions for sports and talk programming. Both have enlisted help from automakers in marketing the services, under which users pay a monthly fee for coast-to-coast access to hundreds of channels, many of them commercial-free.

Sirius brought in radio shock jock Howard Stern (search) in October with a five-year deal that is worth about $500 million. XM later announced an 11-year, $650 million deal with Major League Baseball (search), and Sirius has signed up the NFL.

Sirius also brought in Mel Karmazin (search), the former president of media conglomerate Viacom Inc., as its new CEO last month, replacing Joseph Clayton, who is staying on as chairman.

In trading Monday, shares of Sirius rose 38 cents, or nearly 5 percent, to $8.33 on the Nasdaq Stock Market, where shares of XM rose 10 cents to $40.02.