At The Motley Fool, we poke plenty of fun at Wall Street analysts and their endless cycle of upgrades, downgrades, and "initiating coverage at neutral." So you might think we'd be the last people to give virtual ink to such "news." And we would be -- if that were all we were doing.

But in "This Just In," we don't simply tell you what the analysts said. We'll also show you whether they know what they're talking about. To help, we've enlisted Motley Fool CAPS, our tool for rating stocks and analysts alike. With CAPS, we track the long-term performance of Wall Street's best and brightest -- and its worst and sorriest, too.

And speaking of the worst ...
I come bearing good news and bad news for Nucor (NYSE:NUE) shareholders. The good news: Your stock just got upgraded, and as a result, it headed higher on Thursday.

But here's the bad news: You know who recommended it, right? It was Citigroup. And while reports of the upgrade have focused more on positive outlook for the industry, rather than any specific positives of Nucor's operations, there's one thing we do know: When it comes to picking steel stocks, you have to look long and hard to find an analyst with a worse record than Citi.

Let's go to the tape
Don't believe me? See for yourself:

Stock

Citi Says:

CAPS says:

Citi's Picks Lagging S&P By:

United States Steel  (NYSE:X)

Outperform

****

19 points

Arcelor Mittal  (NYSE:MT)

Outperform

*****

34 points (three picks)

Mechel OAO  (NYSE:MTL)

Underperform

****

199 points (And no, that's not a typo.)

Now, I'm not saying Citi is all bad. It's had more success with metals of a ruddier hue, including copper and gold. And Citi's even picked the odd winner in the steel sector from time to time:

Stock

Citi Says:

CAPS says:

Citi's Picks Beating S&P By:

Randgold Resources (NASDAQ:GOLD)

Outperform

***

68 points

Freeport-McMoRan Copper & Gold (NYSE:FCX)

Outperform

****

23 points

Steel Dynamics (NASDAQ:STLD)

Outperform

****

37 points

But on balance, this banker really doesn't seem to know which side of an arc furnace is the shootin' end. Our CAPS database previously registered a Citi buy recommendation on Nucor in March, 2008; the stock went on to underperform the market by seven percentage points. And Citi's also proven itself a three-time loser on steel giant Arcelor Mittal. Literally every time it's told people what to do with the stock, investors have lost money.

The Ed McMahon of bad news
Here's my real fear: If you follow Citi's advice on Nucor, this could happen to you.

Consider that right now, Nucor carries a sky-high 30 P/E -- totally unreasonable in light of consensus calls for 5% long-term growth at the company. And while I admit that Nucor is a stellar business, generating free cash flow far in excess of reported earnings ... I'm sorry folks, but the stock is still carrying a P/FCF ratio of 10 -- not low enough for a 5% grower, not to my way of thinking.

So maybe Nucor's a better steelmaker than all the others; I won't argue otherwise. But a "better company" does not necessarily a "good investment" make.

Foolish takeaway
You've all heard the saying: "Buy the rumor, sell the news?" Well, this is the time to act on that advice. Nucor's good news just gave investors a small bonus. Cash that check.

And send Citi a thank-you note.

Fool contributor Rich Smith does not own shares of any company named above. You can find him on CAPS, publicly pontificating about stuff he does understand under the handle TMFDitty, where he's currently ranked No. 762 out of more than 140,000 members. The Motley Fool has a disclosure policy.