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 Exelon (NYSE:EXC) slipped 1% today after Jefferies downgraded the electricity company from hold to underperform.

So what: Along with the downgrade, analyst Paul Fremont lowered his price target to $24.50 (from $29), representing about 15% worth of downside to yesterday's close. While contrarian investors might be attracted to the stock's steady plunge over the past six months, Fremont believes that there's still room to fall given Exelon's seemingly below-average assets and cash flow generation.

Now what: Jefferies isn't too high on Exelon's prospects going forward. "The company currently trades at a group average P/E but, in our view, should trade at a discount based on the significant contribution of supply and other low multiple businesses to Exelon Generation results," noted Jefferies. "Additionally, the high cash spending of Exelon on nuclear fuel and maintenance results in very little free cash flow generated by the company." With Exelon shares now off 25% from its 52-week highs and sporting a 4%-plus dividend yield, however, I've got to think that the current price is closer to the floor than the ceiling. 

Fool contributor Brian Pacampara has no position in any stocks mentioned. The Motley Fool recommends Exelon. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.