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 daily-deal specialist Groupon (NASDAQ:GRPN) surged 11% today after Deutsche Bank upgraded the stock from hold to buy.

So what: Along with the upgrade, Deutsche Bank analyst Ross Sandler increased its price target on the stock from $6 to $10, representing about 45% worth of upside to Thursday's close. While Groupon continues to face a maturing market for daily deals, Sandler cited management's increasing focus on its mobile strategy as a potent catalyst for growth going forward.

Now what: Sandler expects Groupon's billings to rise 20% and said that its recent initiatives could result in EBITDA being 30% higher than previously thought. "Sentiment has improved since our initial November 'warm-up,' and now we are upgrading amid the current transition phase before growth turns back up," Sandler wrote in a note to investors. Of course, with the stock now up about 50% over the past three months and trading at a forward P/E of 30, much of that turnaround optimism might already be baked into the valuation.

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