Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of futures broker MF Global (NYSE: MF) are looking increasingly like their future will be dim, falling yet again, this time by as much as 31%, as investors became increasingly worried about the company's capital position.

So what: At the center of the mess at MF Global is CEO Jon Corzine, a plan to turn the brokerage into a serious competitor to Goldman Sachs (NYSE: GS) and Morgan Stanley (NYSE: MS), and a big bet on European sovereign debt. Obviously, that big bet hasn't gone the way that MF Global had hoped, and though yesterday's developments could have been some good news, the downward confidence spiral seemed to have too tight a grip for investors to give the stock a break.

At this point, Moody's (NYSE: MCO) and Fitch have cut MF Global's credit rating to junk, while Standard & Poor's has threatened to do the same. The company has hired Evercore Partners (NYSE: EVR) to represent it in a potential sale, but reports out so far suggest that no white knights are readily stepping up.

Now what: Like Lehman Brothers and Bear Stearns (remember them?) we're talking about a confidence business here. MF Global relies on customers and counterparties -- particularly counterparties that provide repo funding -- to keep the engines running. As we saw with the failed firms above, when confidence starts to drop drastically, it can be very, very tough to pull out of that tailspin. MF Global's assets total around $40 billion. At the end of 2007, Lehman Brothers' were at close to $700 billion. With that in mind, it would seem that a government-led deus ex machina is probably not in the cards, so investors may want to cross their fingers that Evercore is able to work some magic.

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