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

What: Shares of Southwest Airlines (NYSE:LUV) gained 1% today after Stifel upgraded the regional airline operator from hold to buy.

So what: Along with the upgrade, analyst Joseph DeNardi planted a price target of $30 on the stock, representing about 15% worth of upside to yesterday's close. So while momentum traders might be turned off by Southwest's recent pullback, DeNardi's call could reflect a sense on Wall Street that the concerns surrounding the airline's growth trajectory are becoming overblown.

Now what: According to Stifel, Southwest's risk/reward trade-off is rather attractive at this point. "We believe the recent pullback in airline share prices offers an attractive entry point as we expect the focus to shift away from the negative data points of Lufthansa and Iraq towards the strong performance airlines are likely to report over the next few quarters," said DeNardi. "[W]e view Southwest as best positioned to benefit from this dynamic given that (1) it has the highest exposure to the strong domestic pricing environment and (2) no direct risk related to the revenue uncertainty associated with the Pacific and Atlantic markets." Of course, with Southwest shares still up 115% from their 52-week low and trading at a 20-plus P/E, I'd hold out for an even wider margin of safety before betting too heavily on that outlook.