If I can offer some words of encouragement to frustrated Sirius XM Radio (Nasdaq: SIRI) investors, it would be this: It's not you. It's not the stock. It's the market.

Shares of the satellite-radio giant dipped below the $1 mark again this morning. Flirting with both sides of the decimal point have become part of the art of ownership, but this month's brush backs may seem cruel.

  • Sirius XM closed at $1.23 on May 3. It posted a better-than-expected profit the next morning. By the end of the week it had dipped below the $1 mark during intraday trading.
  • Sirius XM clawed its way back to close at $1.07 last week. It kicks off this week by raising its guidance. The market liked the news initially, but now the stock is back under a buck.

Remember when good news used to move stocks higher? In the long run, that will certainly be the case. However, Sirius XM has always been a high-beta stock. It tends to exaggerate general market moves.

According to DailyFinance, Sirius XM's shares currently carry a beta of 1.91. That may seem like a low number, but it basically implies that the stock will be nearly twice as volatile as the S&P 500. This is bad when the market's iffy, although investors weren't complaining when Sirius XM was soaring during last year's buoyant market.

This doesn't mean an investor should dismiss the fundamentals. Sirius XM investors should be watching the monthly sales figures out of Ford (NYSE: F), GM, and Toyota (NYSE: TM) because we already know that nearly half of new-car buyers who check out their free Sirius or XM trials convert into paying subscribers. Any action that Liberty Capital (Nasdaq: LCAPA) takes regarding its 40% stake in the company, positive or negative, will naturally move the stock as well.

Healthy quarterly results and inspiring guidance will ultimately dictate where Sirius XM hangs its hat, but the market's general direction will continue to play a major role in where the short-term gyrations take investors.

The dollar menu isn't always a fun place to be, but history shows that Sirius XM rarely stays in one place for too long.

Where do you think Sirius XM will be trading by the end of this year? Share your thoughts in the comments box below.

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Longtime Fool contributor Rick Munarriz is a subscriber to both Sirius and XM, but he owns no shares in any of the stocks in this article. He is also a member of the Rule Breakers analytical team, seeking out the next great growth stock early in its defiance. The Fool has a disclosure policy.