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) are up over 14% today, on multiple bullish reports surrounding the company's impending earnings report, set to be released next Tuesday.

So what: The bullish sentiment began earlier this week, and Millennial is already up over 20% in the past five trading days. Much of that rise occurred yesterday and today, buoyed by the sentiment of Janney Montgomery Scott analysts on Wednesday, who claim that 2013 will be an "inflection point in the mobile advertising industry," and then by a Seeking Alpha post on Thursday afternoon that made similar claims. This morning, an Oppenheimer analyst pointed out that limited short-term competition and a market-wide trend of earning-season short squeezes should be positive drivers on Tuesday. (Millennial has high short interest.)

Another reason for the rise could be reports that Millennial is in talks to buy Metaresolver, which provides a buying platform for mobile advertisers. This has gotten less play, and seems to be less of a reason for a huge move, but is worth noting nonetheless.

Now what: The old "buy the rumor, sell the news" cycle is in high gear for Millennial right now. With heightened expectations now baked into the price, how much upside could there be on Tuesday? Oppenheimer is holding firm to its $19 price target, and Millennial might get there in time, but caution should be exercised before jumping into a stock that's just risen this much without any sensible catalysts.

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