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 Rocket Fuel Inc. (NASDAQ:FUEL) bounced back 5% this morning after BMO Capital upgraded the artificial-intelligence digital advertising company from "market perform" to "outperform."

So what: Despite the upgrade, analyst Daniel Salmon lowered his price target to $50 (from $65), representing about 32% worth of upside to yesterday's close. While momentum traders might be turned off by Friday's big drop -- fueled by a disappointing Q3 -- Salmon believes that the punishment was overdone, presenting patient investors with a tasty turnaround opportunity.

Now what: BMO sees Rocket Fuel's risk/reward trade-off as a rather attractive at this point. "Weak results and guidance from Tremor Video (TRMR, Not rated, down 49% on Friday) exacerbated a valuation reversal for the ad tech group that peaked around the Criteo (CRTO, Not Rated) IPO on Oct. 30," noted BMO. "FUEL's 3Q13 revenue of $62.5 mn (+132% yoy growth) beat our estimate of $59.5 mn and consensus of $59 mn. The revenue retention rate of 178% (i.e., current client budgets up 78%) held up well versus the seasonally stronger 2Q (180%). And social-mobile-video revenue tripled yoy to 26% of the total, helping power 40 bp of revenue ex media cost margin expansion." Of course, when you consider the long-term margin and competitive uncertainty still surrounding Rocket Fuel's business model, conservative Fools would probably do well to maintain their distance.