XM Satellite Radio Holdings Inc., the nation’s largest satellite radio service, reached an 11-year, $650 million agreement to broadcast Major League Baseball games.

XM Satellite, based in Washington, is adding attractions to maintain its subscriber lead over Sirius Satellite Radio Inc., the no. 2 pay-radio service. Beginning in 2005, XM Satellite will broadcast the games, the company said in a statement. It also will create a Major League Baseball channel featuring original content and classic games.

Both companies are spending hundreds of millions to secure programming they think will lure listeners. Sirius is paying $220 million to broadcast National Football League games for seven years and $500 million to air Howard Stern’s show for five years beginning in 2005. Those investments may not pay off, said a money manager with FA Asset Management, John LaForge.

“What else is left?” Mr. LaForge said in an interview from Sarasota, Fla. “Give me either another radio personality or another sports announcement or something that is a real attraction that gets these guys into the news and attracts new subscribers. I can’t name one anymore.”

Mr. LaForge doesn’t own any XM Satellite shares and said he probably will sell Sirius stock.

After Sirius announced its contracts with the NFL and Mr. Stern, XM Satellite said it had passed on those deals because they were too expensive.

Four days after Sirius announced its contract with Mr. Stern, XM began broadcasting a show with former New York radio personalities Opie and Anthony, who had been fired twice in four years for controversial on-air stunts.

“This will help differentiate their services at the retail distribution level,” said an analyst at Janco Partners Inc. in Colorado, April Horace. Ms. Horace has a “buy” rating on XM shares and doesn’t own any. “The difference between the NFL and the MLB is that baseball already has a very large audience that listens to it on the radio.”

XM Satellite Radio shares rose 13 cents to $29.18 in Nasdaq Stock Market composite trading at 12:30 p.m. Sirius shares fell 3 cents to $3.76.

XM Satellite Radio earlier this month said it had 2.5 million subscribers in the third quarter. The company expects to exceed 3.1 million customers by year-end, higher than its earlier forecast of 2.8 million.

Sirius announced yesterday it passed the 700,000 subscriber mark and reaffirmed its goal of reaching 1 million customers by year-end. The company has said it needs 2 million to break even.

Broadcasting baseball games “is the fastest way for us to grow our credibility,” XM Satellite’s chief executive officer, Hugh Panero, said in an interview, declining to project how many subscribers baseball would lure to the service.

XM Satellite will air about 2,400 games each year, involving all of baseball’s 30 teams. The company already broadcasts Nascar auto racing and some college sports.

XM Satellite charges $9.99 per month for 68 channels of commercial free music programming and 55 channels of news, sports, talk, traffic, and weather. Sirius charges $12.95 a month for more than 100 channels.