Investors are hooked on switching channels with Sirius XM Radio (Nasdaq: SIRI), and I'm not talking about turning the dial on the satellite radio service itself. There's a whole lot of buying and selling of the stock.

More than 354 million shares were traded last week, more than any other Nasdaq-listed company. Only Bank of America (NYSE: BAC) experienced greater trading volume.

This isn't really a surprise. Sirius XM's small share price and volatile trading history have made it a fixture on actively traded lists. However, now that Sirius XM has established itself above the $2 price point, we're not talking about shares that can be purchased with pocket change anymore. It's not just speculators trading in and out of the satellite radio star.

Let's serve up two historical points to flesh this out.

Trading volume on Sirius XM was nearly 120 million a day in February 2009, when the stock sank to an all-time low of $0.05. Now let's zoom all of the way up to May of this year, when the stock hit a nearly three-year high of $2.44. Average daily volume in May was nearly 134 million.

The difference between 120 million and 134 million may not seem like much, but this is based solely on share volume. The stock traded between $0.05 and $0.23 during that dreary February two years ago. In other words, the shares being traded this past May were worth between roughly 10 and 40 times more.

Think about that. There isn't just a little bit more of Sirius XM being traded these days. When it comes to the actual wealth being transferred on these transactions, the difference is huge.

Sirius XM's most active month -- in terms of share volume -- was March of last year. A whopping 177.8 million shares were trading on an average day. However, the stock spent most of that month trading for less than a buck. Once again, the value of the actual trading was substantially greater this May.

Level 3 Communications (Nasdaq: LVLT) is another low-priced regular on the list of Nasdaq's most actively traded equities. The enterprise services provider has also seen the value of its trading volume spike, as it, too, is trading near a three-year high. Level 3 didn't sink to the nickel and dime depths of Sirius XM, but the stock has been on a tear lately. Level 3's stock has more than doubled so far in 2011.

Speculators will no doubt continue to weave in and out of Sirius XM and Level 3. These are high-beta stocks that never provide a dull moment to its holders. However, the booming volume as their share prices move higher indicates that it's not just small lottery players here. Yesterday's speculative investments are gaining institutional and mainstream respect. That's the kind of volume that is louder than words.

Would you rather buy Sirius XM or Level 3 at this point? Share your thoughts in the comment box below.

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Longtime Fool contributor Rick Munarriz is a subscriber to Sirius since 2004. He does not own 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.