They are also harnessing a lot of market-related rage. The gruesome stock plunge of late 2008 and early 2009 was a searing, fool-me-twice moment for many people. The market again seemed hopelessly treacherous, a mug’s game. And if you had an account with the brokerage arm of any number of Wall Street stalwarts — like Lehman Brothers, Citigroup or Merrill Lynch — your losses were doubly galling. Your team helped put a sleeper hold on the economy, the near-collapse of which then ravaged your portfolio.

Even many of those who took the safe route and years ago bought index funds have seen little upside. Look at the performance of the Standard & Poor’s 500, the most popular index out there. If you put $1,000 in it in 1999, you now have slightly less money in your account (about 0.3 percent less, actually).

If the motto of the original day-trade boom was, “If the pros can do it, so can we,” the motto today is, “We can’t do much worse than the pros.”

“There’s this idea out there that retail investors are dumb,” says Howard Lindzon, the co-founder of StockTwits, which curates a gusher of stock tips and financial news alerts tweeted by 20,000 regular contributors. “Well, it turns out that the institutional investors are pretty dumb. They nearly blew us all up with leverage.”

Of course, anyone hoping to join the day-trade caravan had better wear a seat belt, as Mr. Lindloff’s experience on this Wednesday morning demonstrates. Before lunch, he will buy and sell about 44,000 shares, in 17 trades. He starts off poorly, losing about $500. But a timely bet on a company called Rackspace Hosting (“I don’t know what they do,” he says), as well as quick investments in Applied Materials, Eagle Bulk Shipping and a few others, have turned things around.

“Up $210,” he says, removing his headset. Factoring in commissions, he’s made $60.

IT is hard to say how many day traders are currently plying their craft, if that is the right word, in this country. Brokerage firms track the activity and demographics of their customers, but they have been reluctant to share that data. About the most we know is that the day traders skew male, and the number of trades per $100,000 in client dollars is a little less than half what it was back in 2000, according to the Charles Schwab brokerage firm.

Even that figure seems high. As a job, “day trader” registers in roughly the same way as “disco ball manufacturer” or “Brooklyn farmer.” You know that someone has to be making disco balls and that maybe there are still a few plots of arable land in Brooklyn.