Image source: Sirius XM.  

It's getting even more crowded in the bearish camp for Sirius XM Radio (NASDAQ:SIRI). There were 195.1 million shares of the satellite-radio provider's stock sold short as of mid-May, another 52-week high in pessimism for the media giant's stock.

The number of naysayers hoping to profit from the stock's decline has been on the rise since bottoming out at just 139.8 million shares shorted as of mid-February. Short interest has moved sharply higher in five of the six subsequent semi-monthly reporting periods, rising nearly 40% in a span of three months.

One can argue that the pessimism is unwarranted. Sirius XM stock has traded in a relatively tight range, meandering between $3.29 and $4.20. That may seem like a big divide, but it's a small range historically speaking.

It's not fair to call it boring -- no stock that's been an 80-bagger since bottoming out seven years ago can be called that -- but it has become a steady performer. It has a long streak of interrupted profitability, now up to 21 consecutive quarters of positive earnings, according to S&P Global Market Intelligence data.

Proving the growing number of boobirds wrong

Sirius XM seems to be doing everything right by bullish standards. Beyond its ability to stay in the black since 2010, this has proven to be a freakishly lucrative media monopoly. Sirius and XM struggled with chunky deficits on their own, but they have been rolling after a bumpy two-year integration following the completed merger. 

Revenue is growing, and actually accelerated in its latest quarter as a result of subscribers paying more for the service, and advertisers willing to pay more to reach those subscribers on the non-commercial-free channels. Earnings and adjusted EBITDA have been growing even faster, as Sirius XM cashes in on the scalability of the model. 

There are now more than 30 million subscribers, and there's only been one time in the past six years that Sirius XM failed to deliver sequential subscriber growth. Conversion rates have been slipping -- a natural byproduct of deeper market integration as it reaches the masses -- but it's been making it up in volume. Who cares if nearly 55 million of the 85 million cars with satellite receivers are dormant, as long as the subscriber count keeps moving higher?

The shorts clearly see things differently. Short interest doesn't increase out of indifference.

It may just be the people who own Liberty Media's (NASDAQ:FWONA) new tracking stock are shorting the direct investment as a way to lock in the difference in value; but more than likely, it's people who just think the stock is heading lower. That's a dangerous proposition when the fundamentals don't show any immediate signs of cracking.