Buy Young, Sell Young

His buddies were intrigued by Microsoft after the antitrust ruling, so he went online to snap up stock. The price jumped $20 a share. It was a classic case of right place, right time. Except that Jason Marchione is not your classic investor. His lucky tip came in the middle of fifth-grade computer class. "There's that famous quote," says Jason, 11. "Buy low. Sell high. Make mad dough."

Once upon a time, the eyes glued to financial news would have had to wear bifocals. But the stock market, like sex, is no longer just adult fare. The Internet pumps quotes, research...