While Fools should generally take the opinion of Wall Street with a grain of salt, it's not a bad idea to take a closer look at particularly stock-shaking upgrades and downgrades -- just in case their reasoning behind the call makes sense.

What: Shares of Groupon, Inc. (NASDAQ:GRPN) climbed 3% this morning after Northland Capital Markets initiated coverage on the daily-deals specialist with a buy rating.

So what: Along with the buy rating, Darren Aftahi planted a price target of $13 on the stock, representing about 22% worth of upside to yesterday's close. The stock has been sluggish in recent months on concerns over waning demand, but Aftahi believes that Groupon's transition from a pure "daily deals" play into a more diversified marketplace should help reignite its breakneck growth.

Now what: Northland thinks management's strategy translates well to both mobile and local offerings. "[Groupon's] recent platform expansion to include brand discounts and coupons (Freebies), enhanced contextual search, emphasis on mobile, and eventual broader expansion into discounted 'productized services' should increasingly make it a destination platform, connecting engaged consumers searching for local deals and merchants looking for a broad channel to promote local commerce offerings," noted Northland. Of course, with the stock still trading at a forward P/E of more than 40, much of that optimism might already be baked into the valuation.