Markets are not perfect and as well as the arbitragers perform, timing differences remain.

FORBES: You Call It Inflation, I Call It Theft

"If investors, treasurers and arbitragers get more optimistic, we could see more" buyouts, takeovers and stock buybacks, which might help stocks, Mr. Ablin says.

WSJ: Stocks Testing Records��But There's Still Room to Run

They can also act as arbitragers, exploiting differences between the two markets, or use the pits as a way to cancel a trade if the strategy doesn't work.

FORBES: Companies, People, Ideas

Software billionaires tend to be more cuddly than arbitragers.

FORBES: Follow-through

Already, the search engine has spawned businesses such as search-engine marketing and optimization, or Web arbitragers, and companies that live by serving Google's voracious computing needs (see: " The Search Industrial Complex").

FORBES: Magazine Article