The market has handed investors some nice, consistent returns over the long run, but in the short term it can often be as unpredictable as an episode of Adventures in Hollyhood. In a pair of articles, I explored the market's so-called "fat tail" distribution -- the tendency of stocks to make huge moves that seem extremely statistically improbable. Since then, I've been following "five-sigma moves," or one-day price moves that are five standard deviations or more from a stock's average one-day change.

Keep in mind that we're looking at the price change relative to the stock's historical volatility, and not just the same old jittery "most active" stocks. So even though stocks like Novatel Wireless, On2 Technologies, and Harris & Harris Group saw some big movement last week, you're not going to see them on this list because of their higher average volatility.

Here's a taste of a few of the five-sigmas from the past week:





CAPS Rating

Gerber Scientific (NYSE:GRB)





Odyssey Marine Exploration (AMEX:OMR)










Quanex (NYSE:NX)





Copa Holdings (NYSE:CPA)





Sources: Yahoo! Finance, author's analysis, and CAPS as of May 21.

It's important to note that when I looked at stocks that made five-sigma moves in the past, they didn't always move in a predictable fashion following the event. In other words, not all of the stocks that jumped way up turned back down, nor did all of the stocks that fell through the floor start to bounce back up.

The key is to figure out whether the big move was because of a legitimate change in the company's fortunes, or whether it was simply investor overreaction. To get a better idea of which of these stocks might be worth a deeper look, I got some help from The Motley Fool's new CAPS investing community.

A pirate's life for me
It was an exciting week for Odyssey Marine shareholders last week. On Thursday, the company announced that it had made a major find, and on Friday the stock shot up more than 80%.

Odyssey Marine describes itself as a company that engages in "archeologically sensitive exploration and recovery of deep-water shipwrecks." In other words, they're treasure hunters. The company uses a combination of historical records and modern-day high-tech equipment to find and search deep-water shipwrecks and recover all sorts of goodies from them.

As you might expect, this is a hit-driven business. Odyssey focuses primarily on wrecks that the records show were carrying a significant amount of valuable materials, since the costs of finding, exploring, and recovering artifacts from these shipwrecks is so high. But for all the up-front investment, there's never any guarantee about how much will actually be found.

Last Thursday, those investments seemed to pay off in a big way. Odyssey's find, code-named "Black Swan," reportedly contained 500,000 silver coins, some gold coins, and some other potentially valuable artifacts. The company has revealed that the silver coins could have a retail value between a few hundred dollars and $4,000 each, and it has been reported elsewhere that the likely median price could be $1,000 -- which would give the find a value of $500 million or more.

It's important to remember that there are still a lot of question marks on the find. Of course, the exact value of the coins is still unknown. Also, claims are also sometimes made on these finds by governments -- on Odyssey's HMS Sussex project, for instance, there is an agreement to split potential findings with the British government. Additionally, even assuming a $500 million value for the find, it doesn't all go to the bottom line for Odyssey. There will be significant costs associated with the identification and restoration of the artifacts, and there will also be transactional costs associated with actually selling what they've found.

Uncertainties aside, as I write this the market is valuing Odyssey at $396 million. That value would ostensibly include some probability-weighted value of the Black Swan find, the value of Odyssey Marine's shipwreck operations and future finds, and the potential value of Odyssey's planned themed attractions. The company also confirmed today that it has entered into a relationship with Disney (NYSE:DIS) (that's right, the Pirates of the Caribbean Disney).

CAPS players have given Odyssey a rock-bottom one-star rating. Even after the recent find, players such as CAPS All-Star Kinzo have questioned the long-term potential of the stock. He shares:

How many shipwrecks are out there that will support this operation? This recent find was indeed huge and potentially worth [hundreds] of millions. However, I feel that future finds will most likely be few and far in-between. THUMBS DOWN short-term.

There are a good number of bulls on the stock, though, and they include se7ensparks, who spoke out in favor of the stock prior to the recent huge find:

[Odyssey] has developed technology to enable it to explore for sunken treasure. It has made arrangements with foreign governments to retrieve lost treasure and will keep much of what it finds. ...

It's an unusual company doing an unusual type of business. But, then again, there have been a tremendous number of sunken ships that have carried vast wealth over the ages.

If the company makes a big score, this stock could take off and make for a great Return On Investment. Or, as we in the pirate-sunken-treasure business say, a great AARRRRRGGHH-O-I.

So far, 77 CAPS players have chimed in on Odyssey, and there's always room for more. Take a stroll on over to CAPS and let the community know what you think of the opportunity at Odyssey. And while you're at it, check out some of the other five-sigma stocks mentioned above -- or a few of the other 4,500 stocks on CAPS.

Fool contributor Matt Koppenheffer enjoys his weekly statistical rendezvous even more than he likes watching Computer and Big Triece mix it up on Hollyhood. He does not own shares of any of the companies mentioned. Disney is aMotley Fool Stock Advisor choice. Harris & Harris is aRule Breakers selection. The Fool's disclosure policy has passed the mandatory drug screening and is cleared to help you continue hitting home runs.