Sirius Satellite Radio Inc. (NASDAQ: SIRI) and XM Satellite Radio Holdings Inc. (NASDAQ: XMSR) surged yesterday after Citigroup analyst Eileen Furukawa estimated that the proposed multibillion-dollar merger has a greater than 60% chance to succeed. The analyst believes regulators have shifted in favor of the merger and that the market, currently giving the deal only a 24% chance of passing regulatory muster, is underestimating the chances and is too bearish. Furukawa has upped XM's price target to $19.50 from $15.

Still, if the merger goes through, Furukawa estimates it could produce up to $7.2 billion in cost savings and further, this estimate might be conservative as it does not include capex savings. In addition, the merged company could drive higher ad revenues and move away from the subscriber-based model into the ad-revenue one that seems to be where many believe the money is, especially as the early subscriber growth both companies experienced has cooled.

If the merger indeed succeeds and the cost savings are achieved, there may be a chance the combined company could rediscover the earlier growth it once witnessed. As Dana Cimilluca of the WSJ Deal Journal notes, this cost savings is bigger than XM's market cap of $4.67 billion, so no wonder both companies and their shareholders pushed the merger forward so passionately. They know what might happen if the merger doesn't go through.

One last comment on this. Contrary to Furukawa, Jonathan Jacoby of Banc of America Securities thinks that the stocks' recent prices actually imply that investors think there is an 85% chance of the merger succeeding. I'm not sure what could explain such a big difference in the two opinions, but I do know what mine has been all along and why I'm in trouble with many satellite fans. I do believe these to be too risky for their potential upside and I'm staying out.

Tuesday, SIRI shares closed up 3.77% to $3.5799 and XMSR shares up 6.87% to $15.24. Today, XM shares are cooling a bit, down over 1% to $15.08, while Sirius shares are continuing to climb, up more than 3% to $3.69 by midday.

The release date of XM Satellite Radio Inc.'s (NASDAQ:XMSR) Q4 2006 earnings report is thus far unannounced, but could come as early as next week. The uncertainty about that date seems to reflect a larger uncertainty about XM and its only real rival, Sirius Satellite Radio Inc. (NASDAQ:SIRI).

Share prices of both satellite radio broadcasters rose for a time in January as rumors swirled that XM and Sirius might merge, even though it would require changes to FCC rules to make the merger possible. Analysts' reactions to the possible merger were mixed, depending on whether they thought the merger was likely to pass muster, when it might happen, and what such a merger might do the value of the resulting stock: