Sirius Satellite Radio Inc. picked up a significant number of new customers, leading to a big increase in second-quarter revenue, but still trails far behind competitor XM Satellite Radio, Inc.

New York-based Sirius finished the second quarter with 1.81 million subscribers, a 59 percent increase in subscribers compared to the same period a year ago, when the company had 1.14 million subscribers. Sirius filed its 2005 second quarter financial report Aug. 3.

XM Satellite Radio of Washington, by contrast, finished the second quarter with 4.42 million subscribers, a 110 percent growth over its 2.1 million subscribers at the end of the 2004 second quarter. The company added 647,226 subscribers in the 2005 second quarter.

The increased subscriber-base for Sirius offered a boost to revenue, which came in at $52.19 million for the quarter, $49.62 million of that from subscribers. In 2004, revenues were at $13.23 million at the end of the second quarter.

Operating expenses, however, also were up, at $226.78 million for the second quarter, compared to $146.22 million in 2004. Sirius ended the quarter with a net loss of $177.55 million, $40.75 million more than its second quarter losses in 2004.

The company has operated at a loss since its inception, and said in the report it expects to continue to do so “until the number of our subscribers increases substantially.”

Sirius will have to contend with even higher operating expenses as its high-profile additions of radio personalities and sports programming begin to take effect. Its contract with U.S. entrepreneur Martha Stewart begins in the third quarter, and agreements with shock-jock Howard Stern and for NASCAR broadcasts are scheduled to follow in 2006 and 2007, the report said.

The quarter also saw the announcement of an agreement between Sirius and Ford Motor Company of Dearborn, Mich., to have an exclusive relationship until September 2011, through which Sirius will supply satellite radio receivers to be installed in Ford vehicles upon a customer’s purchase or lease.