The men at the stock exchange got to wear their 10,000 hats and market watchers cheered that the magic number of 10,000 for the Dow Jones industrial average was passed yesterday for the first time in a year. But who made it happen? The Washington Post reported Thursday that individual investors sat out the recent rally. While large pension-fund managers and hedge-fund owners are cheered by the charge, mom-and-pop investors remain on the sidelines. In fact, financial planners tell the paper, only very recently have individual investors begun to take notice. Said one: "For the first six months of the year, people just had their heads down. I don't know how many people told me they haven't looked at their statements."