XM SATELLITE RADIO HOLDINGS ANNOUNCES FIRST QUARTER 2000 RESULTS

Approximately $1 Billion in Gross Proceeds Raised by XM Radio to Date New Deals Put XM's Next Generation Service on Land, Sea and Air

National, April 21, 2000 -- XM Satellite Radio Holdings Inc. (NASDAQ:XMSR), ("XM Radio") an innovator in radio entertainment, today reported financial and operating results for the first quarter ended March 31, 2000. During the quarter, XM Radio's management team raised additional gross proceeds of $565 million, signed a series of strategic distribution and marketing deals with leading companies such as Freightliner, SFX and AVIS, and formed an alliance with Sirius Radio to develop a unified standard for satellite radios.

First Quarter Financial and Operating Results
The company reported first quarter operating loss (EBIT) of ($16.9) million, a net loss of ($12.7) million, and a net loss available to common stockholders of (14.2) million, or ($0.30) per share, as compared to an operating loss of ($4.4) million and a net loss of ($4.4) million, or ($0.65) per share, for the first quarter of 1999.

During the first quarter 2000, XM Radio raised gross proceeds of $565 million through the successful offering of 4.37 million shares of common stock, 2 million shares of 8.25% series B convertible redeemable preferred stock, and units consisting of 14% senior secured notes and warrants for $140 million, $100 million and $325 million, respectively. The company has raised total net proceeds of $865 million toward the launch of its commercial service in the first half of 2001.

Hugh Panero, XM Radio's President and CEO said: "XM Radio's continued success in raising funding validates the strength of our innovative business model and the tremendous potential of our market opportunity. At the same time, the range of powerful distribution and marketing alliances we've established ensures XM Radio exposure to listeners everywhere: where they play, work and travel; in concert halls, theaters and sporting venues; and in trucks, airplanes, rental cars and boats."

Panero continued, "Together with our best of industry partners, XM Radio continues to implement our business strategy and create a whole new national radio platform, complete with unique, 'must hear' programming. Our partnerships with leading advertisers and consumer electronics manufacturers and high profile marketing, distribution and technology companies are enabling XM Radio to deliver the next generation of radio on budget and on schedule."

Company Announces Key Marketing Relationships, Technology Agreements
XM Radio in the first quarter announced several important technology agreements. The company awarded its satellite systems operation contract to Telesat Canada, the world's most experienced satellite operator. Other key developments during the quarter included new marketing agreements with SFX Entertainment, LiveTV and Avis Rent A Car. The multi-year alliance with SFX will allow XM Radio to quickly and effectively reach 60 million consumers annually through SFX events and concert venues. By partnering with Avis, one of the most respected brands in the car-rental industry, XM Radio will also reach potential subscribers on their vacations and business trips. XM Radio also strengthened its distribution channel in deals with Freightliner, Pana-Pacific, and Marine Audio.

XM Radio is also building the largest all-digital radio studios in the US at its new Washington, D.C. headquarters. Featuring a network of more than 80 inter-connected audio studios to provide the high-quality production required to create its XM Originals cutting-edge formats, XM Radio is set to bring the passion back to radio. In February, XM Radio announced an agreement to develop a unified standard for satellite radios with Sirius Radio. The standard is expected to accelerate growth of the satellite radio industry. The companies also agreed to jointly fund development of the technology and to work together to proliferate the new standard by creating a service mark for satellite radio.

About XM Satellite Radio
XM Satellite Radio is developing a new band of radio. Starting the first half of 2001, XM Radio will beam up 100 channels of digital quality music, news, sports, talk and children's programming directly from its two powerful satellites to vehicle, home and portable XM-Ready radios coast to coast. Listeners will be able to drive from New York to Los Angeles, Chicago to Corpus Christi while continuing to listen to their favorite XM channels without searching the dial as they travel through unfamiliar parts of the country.

The XM sound will combine leading brand-name channels with distinctive formats produced in XM Radio's fully digital Programming Center by some of the country's leading artists, producers, programmers and radio format designers. XM-ready radios will be manufactured by such household names as Sony, Alpine, Pioneer Electronics Corporation, Delphi Delco Electronic Systems, Audiovox, Clarion, Mitsubishi Electronic Automotive America, Motorola and the Sharp Corporation.

The service will be easy to order, with XM-Ready radios available at car dealerships and consumer electronics stores across the country. The company has a long-term distribution agreement with General Motors to integrate XM-Ready radios into its vehicles commencing in 2001. XM will be available to truckers, boaters and airplane passengers through deals with Freightliner and Pana-Pacific, Marine Audio, and LiveTV respectively.

American Mobile Satellite Corporation (NASDAQ:SKYC) holds a controlling interest in the company, which is also backed by General Motors, Clear Channel Communications and DIRECTV, respectively, the leading car, radio and satellite TV companies in the US.

First there was AM, then FM and soon ... XM Satellite Radio. For more information, please visit XM's new website:

Factors that could cause actual results to differ materially from those in the forward-looking statements in this press release include uncertainties associated with the launch of our satellites, the company's dependence on third party vendors, its continuing need for additional financing, as well as other risks described in XM Satellite Radio Inc.'s Form 8-K filed with the Securities and Exchange Commission. Copies of the filing are available upon request from XM Radio' s Investor Relations Department.

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