Things never get dull for the country's lone satellite-radio provider. Shares of Sirius XM Radio (NASDAQ:SIRI) moved lower on the week, slipping 1.3% to close at $3.16.

There was more going on beyond the share-price gyrations, though. Short interest clocked in at its highest level of the year. Sirius XM's debt gets an important update. On the streaming front, Apple (NASDAQ:AAPL) may be gearing up to launch a Spotify-like on-demand service and Pandora (NYSE:P)scored an analyst upgrade.

Let's take a closer look.

She wears short shorts
Given its low share price and heavy trading volume, it isn't a surprise to see Sirius XM atop Nasdaq's list of most shorted stocks. Now that its majority stakeholder isn't publicly proposing to acquire all of the shares, the naysayers are back.

Nasdaq published its semimonthly short interest data on Wednesday afternoon, revealing that there were 242.2 million shares of Sirius XM sold short. It's a big number, but that's a far cry from when it topped 400 million shares 14 months ago. This is still the highest semimonthly figure since the end of last year, and short interest has risen for three consecutive periods since bottoming out at 184.4 million shares on Valentine's Day.

Short interest will probably continue to rise heading into its first-quarter report, and that's fine. Sirius XM has been eating shorts for breakfast through most of the past five years.

Making the grade
Remember when Sirius XM's debt was carried a junk rating? Remember when it had to hand over 40% of the company in a preferred share stake just as a door prize to raise money at a stiff 15% interest rate?

Sirius XM has come a long way. The media giant announced on Thursday that both Standard & Poor's and Moody's have upgraded their ratings on Sirius XM's 5.25% senior notes due 2022 to investment grade.

This isn't just a testament to Sirius XM's improving fundamentals and ability to generate tons of free cash flow. The upgrade also relaxes many financial covenants, freeing Sirius XM to be more aggressive with its share repurchases. 

Apple slices
It may be time for an iTunes overhaul. Billboard ran a story this week about the slowdown at Apple's iconic music store. Apple hasn't offered a lot of color lately on its digital music business, but label executives aren't afraid to paint an unflattering picture. 

Several record labels are telling Billboard that overall music downloads have fallen 15% over the past year. The September arrival of the Pandora-like iTunes Radio was supposed to light a fire in e-commerce, but it seems as if less than 2% of the folks checking out Apple's music discovery service have gone on to make a purchase. 

Billboard expects Apple to roll out an on-demand service along the lines of Spotify and to eventually make iTunes for Android. Apple certainly needs something to make its digital music ecosystem as relevant as it used to be.

Pandora rocks
Pandora shares have fallen sharply in recent weeks, and that's a dinner bell for at least one analyst. Wedbush's David Pachter is upgrading Pandora from "neutral" to "outperform." His $35 price target may seem ambitious now, but keep in mind that Pandora peaked just above $40 last month.

An upgrade is certainly welcome. A lot of last year's darlings have corrected sharply over the past month, and analysts are starting to feel opportunistic.

A Sirius future
It was an interesting week for Sirius XM. The new week isn't likely to be dull -- and the Oracle of Omaha almost never is. Warren Buffett has made billions through his investing and he wants you to be able to invest like him. Through the years, Buffett has offered up investing tips to shareholders of Berkshire Hathaway. Now you can tap into the best of Warren Buffett's wisdom in a new special report from The Motley Fool. Click here now for a free copy of this invaluable report.

Rick Munarriz has no position in any stocks mentioned. The Motley Fool recommends Apple, Berkshire Hathaway, and Pandora Media and owns shares of Apple, Berkshire Hathaway, Pandora Media, and Sirius XM Radio. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.

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