If the equity markets were an ice skating rink, the mortgage market turmoil would be a hired thug taking a metal baton to the knee of the major financial names. Specifically, the credit market problems have big shots like Goldman Sachs (NYSE:GS), Bear Stearns (NYSE:BSC), and Morgan Stanley (NYSE:MS) smarting in a big way.

Prior to Tuesday's big Fed-fueled rally, Goldman was down nearly 20% from the high it hit back in June -- and that was after already climbing back 14% from its August low. Over the past four quarters, Goldman has produced $21.45 in earnings per share, putting its trailing P/E ratio at 8.7 as of Tuesday's opening price. This low price had members of The Motley Fool's discussion boards talking.

Back in July, longtime Fool mills014 posted to the discussion boards asking "what is driving Goldman's price down?" He cited the subprime concerns as putting pressure on Goldman's stock, but said that "the 20% drop in GS over the last several weeks is a bit ridiculous" and likewise thought that a P/E multiple around 9 was just too low.

Responses to the query ran the gamut from AlejandroOrtiz suggesting that price decline was an overreaction, to mannprod pointing out that Goldman would be hurt by both the end of the buyout boom and the volatility of its hedge funds. As of this writing, the last response in the discussion comes from AlejandroOrtiz, who suggests that the lower price creates a good buying opportunity for long-term investors in what he calls "possibly the best brokerage house on Wall Street."

Although Goldman's stock rallied almost 7% after the Fed's interest rate decision, it is still well below its highs for the year. The firm is also getting ready to report its earnings tomorrow, which could be very revealing. Think you know why Goldman's stock is so low and where it's headed? Sign up for the Fool's (free!) discussion boards and join the debate!

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Fool contributor Matt Koppenheffer does not own shares of any of the companies mentioned. When it comes to cheap stocks, The Fool's disclosure policy always wonders WWWD -- what would Warren do?