Remember Greece? The lovely home of Homer, grilled octopus and, more recently, enough debt to topple a Trojan horse? Well, most U.S. traders barely do. For a few weeks in February, Greece s debt woes seemed to weigh on global stock markets. And then U.S. markets moved on.

That s not to say that Greece s debt problems are over. Yes, there have been some positive developments, but traders really just decided to focus their attention elsewhere, some market watchers say. It s easy to forget what happened yesterday, says Justin Walters, co-founder of Bespoke Investment Group, a money management and research firm.

A shorter attention span may be the product of information overload, Walters says. Traders get bombarded constantly with news from cable TV, their Bloomberg terminals and Twitter accounts. With information flowing so fast, short-term investors digest news quicker than they used to.

Twitter in particular has contributed to this phenomenon in recent years, some say. On Tuesday, the stock of Darden Restaurants (DRI) owner and operator of casual dining restaurants such as Olive Garden and Red Lobster started to decline. Ryan Detrick, senior technical strategist with Schaeffer s Investment Research, an options-trading and investor education firm, looked on the newswires to try to find out why. When he didn t see anything, he turned to Twitter, where he saw that an analyst had downgraded the stock to hold from buy.

Traders attention spans have narrowed even in the few years since Twitter s launch, Detrick says. Market participants hate uncertainty more than bad news, he says, and today s instantaneous flow of information has shrunk periods of uncertainty and helped traders focus more quickly on the next issue of the moment.

What does all this mean for investors at home? Not much, the pros say. It s hard for individual investors to keep up with the news that traders follow. By the time it crosses the front page, it s old news as far as Mr. Market is concerned, says Barry Ritholtz, chief executive and director of equity research for Fusion IQ, a research firm, and author of The Big Picture blog. Besides, most mom-and-pop investors have much longer time horizons than traders, some of whom try to make money in a matter of minutes. Focusing too much on short-term stock movements can derail many investors carefully planned strategies.

Investors with a small active trading allocation can certainly follow their stocks on Twitter for fun (the site StockTwits aggregates the chatter about stocks on Twitter). But keep a critical eye, says Ritholtz: You can t just take an opinion out of context.