The world of commodities is a strange one to outsiders. Not only do you have to navigate weird words like "contango," but you have to deal with contract expirations, daily mark-to-market, and lock limits. Investors in Chicago Mercantile Exchange (NYSE:CME) can be forgiven if they'd like one of those lock limits to kick in on their shares today and stop the slide.

While fourth-quarter revenue for this futures exchange and derivatives super-marketplace grew 42%, both revenue and earnings per share came in below the average Wall Street analyst's guess. The culprit here is lower revenue capture per contract. The company thinks this was a seasonal phenomenon and attributed these drops to a greater proportion of trades being handled by exchange members, who pay lower fees than nonmembers.

In English, that means that the Merc is making less money from each traded contract. Overall, the Merc reported earning $0.703 per contract for the fourth quarter -- up from $0.688 last year but down from the third quarter's $0.717. Pressures on interest rate contracts (which make up more than half of the Merc's volume) were even more severe -- dropping from $0.59 in September to $0.53.

So far, volume has not been a major problem for the Merc. While average daily trading volume has been down for two straight quarters now, total volume is still at record levels. In January alone, more than 3.7 million contracts were traded -- up 30% over last year and above the prior record of 3.6 million set in September.

I don't see any reason to believe futures and derivatives trading are on the brink of imminent decline. The incredible volatility in grain, metals, energy, and foreign exchange markets has generated a lot of wealth for traders and speculators, and new commodity and/or derivative hedge funds have been popping up left and right.

Given that the managers of these funds don't get paid to just sit and stare out the window, I believe there's a strong case for expecting continued high volumes. What's more, the Merc remains one of the best (if not the best) exchanges in the world. Barring suicidal price competition from other competing exchanges, it should continue to grow and prosper.

That said, the Merc's current valuation suggests people already expect that. Even with today's ugliness, the stock trades at more than 30 times trailing earnings. It's perhaps ironic that the Merc's stock got caught up in the same sort of momentum-driven bull run that often happens in the commodities market. And just like those runs, the unwinding process can be swift and brutal at the mere hint of disappointment.

Fool contributor Stephen Simpson, CFA, has no ownership interest in any stocks mentioned.