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 Millennial Media (NYSE:MM) jumped more than 10% Wednesday after an SEC filing showed Millennial CEO Michael Barrett purchased 291,000 shares.

So what: Last Thursday, shares of Millennial Media plunged a painful 37% following mixed first-quarter results and weaker-than-expected forward guidance. Barrett insisted at the time, "While I would have liked to have seen stronger performance in the quarter, we have developed an aggressive strategy and I have high confidence that we can execute and capitalize on the growth and promise of mobile."

The filing shows Barrett -- who took over as CEO in late January -- put his money where his mouth on Monday and Tuesday, spending more than $1 million to increase his stake at an average price just under $3.45 per share. That brings his total stake in Millennial Media to 744,693 shares. 

Now what: I previously suggested Millennial Media's huge drop was likely an overreaction, so I can certainly understand Barrett wanting to set an example in buying shares now. But from a long-term perspective, I'm still not interested in following his lead. For now, I'm content watching Millennial Media from the sidelines to keep tabs on its progress over the next couple of quarters. If Barrett can show more evidence, his strategy will bear fruit over the long term -- and even if it means missing out on some short-term gains, I'll be happy to reconsider down the road.

Steve Symington has no position in any stocks mentioned, and neither does The Motley Fool. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.