(AP) -- Video game publisher Activision Blizzard Inc. said Wednesday that the game "Call of Duty: Modern Warfare 2" has brought in more than $1 billion in revenue since it went on sale in November.

Given that pace, the game is on track to become the best selling video game ever by number of copies sold, said Michael Pachter, an analyst at Wedbush Morgan.

Based on the revenue figure, Pachter said the company has probably shipped about 17 million copies of the game so far. And he expects it to surpass the roughly 23 million copies sold of ": San Andreas," which was released in 2004 and holds the previous record.

"Call of Duty" has an edge because of its online multi-player mode. New updates to the online version can give titles a longer shelf life.

Still, Pachter said he doesn't expect Activision's fourth-quarter financial results to surpass expectations. "They're not killing it, but they're making it," he said.

While "Call of Duty" sales are "impressive," titles such as "" have been lackluster.

Others in the have given indications of weak holiday sales. Rival Electronic Arts Inc. this week slashed its 2009 earnings estimate for the second time. GameStop Corp., the world's biggest retailer, said sales during the shopping season dropped 8.6 percent from the year before.

Activision shares rose 6 cents to $10.83 in afternoon trading.