It has been another good week for Sirius XM Radio (NASDAQ:SIRI), especially if you draw the starting line when shares of the satellite radio operator bottomed out at $0.05 two months ago.

The stock is now an eight-bagger, based on Thursday night's close, and would become a nine-bagger if Friday's intraday highs stick.

The catalyst this week is a welcome nod of approval from credit rating agency Standard & Poor's. It raised its rating on Sirius XM on Tuesday -- to CCC+ from CCC -- two months after an infusion from Liberty Media (NASDAQ:LINTA) improved the radio giant's near-term liquidity.

Sure, it's still a junk-bond rating. And S&P didn't change the rating on Sirius XM's senior unsecured notes. However, it's just another baby step in the right direction for a company that many figured would file for Chapter 11 bankruptcy protection two months ago.

The upbeat news comes at a time when Sirius XM itself has been pretty tight-lipped about its near-term prospects. It abandoned its subscriber targets when it posted its fourth-quarter report last month. The only guidance the company is providing at this point is that it expects to top $300 million in operating profits this year.

Even if all of that is consumed by interest payments on debt, it would be a confidence builder, especially for the company's creditors. A buoyant share price may also grant the company the flexibility to use secondary stock offerings to pay down its debt. It would also help the company step back from considering a reverse stock split, which has ended poorly for most companies, save for priceline.com (NASDAQ:PCLN).

Sirius XM has a long way to go. We have yet to see if likely near-term catalysts -- like the Apple (NASDAQ:AAPL) iPhone app that Sirius XM is releasing this quarter or whispers of a bundled package with satellite television giant DirecTV (NYSE:DTV) -- pan out.

However, as long as the shorts keep coming despite the steady trickle of positive developments, there could be more bags in Sirius XM's future.

More news than static on Sirius XM:

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Longtime Fool contributor Rick Munarriz subscribes to both XM and Sirius. He does not own shares in any of the companies in this story. He is also part of the Rule Breakers newsletter research team, seeking out tomorrow's ultimate growth stocks a day early. The Fool has a disclosure policy.