Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of Leap Wireless (Nasdaq: LEAP) rose more than 14% in early trading and remain up more than 12% as of this writing. Insiders and institutions have stepped up buying as the stock has fallen.

So what: Notable buyers include new board member Richard Roscitt and the MHR Fund, the latter which increased its stake to 25.9% of the shares outstanding, reported.

Now what: The buys are interesting in that they come after a massive plunge in Leap's stock price. Yet the purchases could prove Foolish. Leap trades for 0.20 times sales. Thus, at current prices, the market value of $1 of Leap revenue is just $0.20. Count MHR and Roscitt among those who believe that valuation is unfair. Do you agree? Disagree? Weigh in using the comments box below.

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