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.

What do Whole Foods Market Inc. (NASDAQ: WFMI) and Sirius Satellite Radio Inc. (NASDAQ: SIRI) have in common? What do Wild Oats Markets Inc. (NASDAQ: OATS), Borders Group Inc. (NYSE: BGP) and Google Inc. (NASDAQ: GOOG) have in common? I'll give you a hint -- they all want to merge with some other company in their field. But the mergers are all very different.

Give me a break, one cannot compare the proposed merger between Whole Foods and Wild Oats to that of Sirius and XM Satellite Holdings Inc. (NASDAQ: XMSR). I know many Sirius and XM investors will lash out at me for this, but come on people! Sarah Gilbert made a very good case yesterday why the merger of the trendy food stores doesn't have antitrust issues: "There is a plentiful supply of organic and natural produce and other products available at both small local cooperatives and farmer's markets and large supermarket chains," least of all Wal-Mart Stores Inc. (NYSE: WMT).

Sirius and XM? Now that's a different story altogether. They are the only two satellite radio companies. There are no smaller competitors, or large competitors with a small market share. That's all there is -- Sirius and XM. Sure, the argument that the market includes iPods, internet and HD radios is very creative and may even work, but let's call it what it is -- a desperate attempt by the two companies to get their merger approved. They've even hired a lobbying firm.