Source: Sirius XM on Facebook

Bears are awakening from their hibernation on Sirius XM Holdings (NASDAQ:SIRI). Short interest is starting to tick higher when it comes to the satellite radio provider's stock, and that's actually good news for those that are long Sirius XM.

Let's start by painting a picture of naysayer scene. The market exchanges publish short interest twice a month, and the latest report finds 155.7 million shares of Sirius XM sold short as of mid-May. That's a big number, but the combination of Sirius XM's historical volatility and its low share price have a funny way of bringing out speculators on both ends of this fiscal tug-of-war. 

Sirius XM has routinely been one of the most shorted stocks in the market based on shares outstanding. That picture improves for the bullish when you factor in the low price relative to other heavily shorted equities. 

However, you have to go all the way back to late November to find the last time that Sirius XM had more shares sold short. Short interest bottomed at 130.4 million shares of Sirius XM at the end of March, and it has ticked higher in every subsequent exchange update.

Historically speaking, 155.7 million may not seem like much. There were 318 million shares sold short at the end of June last year, and short interest topped 400 million in early 2013. The stock price is higher than it was a year ago or back in February 2013, so the value of today's bearish wagers is larger than the mere share count suggests. It's still a big number, and that statement of pessimism among speculators could also be the best news that those long Sirius XM could get.

Good news bears
Sirius XM is on a roll, posting reasonable growth in its latest quarter. Revenue and subscriber counts are up 7% and 8%, respectively, over the past year. Earnings and free cash flow grew even faster. 

Shorting Sirius XM has been one of the most dangerous things to do since shortly after the stock bottomed out at  a nickel in early 2009. The bearish thesis will change over the years. 

Sirius XM is going to file for bankruptcy was 2009's lament. Sirius XM was going to lose Howard Stern at the end of 2010. Neither pitfall materialized, and over the past few years we've seen the stock climb the wall of worry posed by the threat of the connected car on premium broadcasting. Sirius XM has earned its way to monster gains, though the stock was essentially flat last year. 

It's starting to move higher again in 2015, and that could possibly be what's drawing out the boo birds. Having shorts around isn't a bad thing. They eventually need to cover their short positions, and that gives the stock the potential for an upside pop if they all scramble for the exits in a short squeeze. So, yes, let the short interest keep inching higher. If they haven't learned from earlier skeptics that got burned for being bearish, history shows that Sirius XM's stock performs at its best when the head shakers are at their busiest.