Shares of Zillow (NASDAQ:ZG) have had an impressive run recently and delivered stellar growth for investors last year, but now, two key insiders among the company's top brass, including CEO Spencer Rascoff, are selling off shares. Should investors be worried?

In this segment from Thursday's Where the Money Is, Motley Fool banking analyst David Hanson takes a question from the mailbag, investigating the insider selling at Zillow. As the old Wall Street adage says, while there is only one reason to buy, there are many possible reasons to sell a stock. David looks at why these two insiders might be selling, and tells investors he's not concerned.