NEW YORK: For three days of the Easter weekend, the stock market gauge had been frozen at 140 below. No sooner did the markets reopen Monday than traders lopped another 157.11 points from the Dow, for the sixth-largest drop in stock market history and the heaviest two-day loss since the Crash of 87. And yet . . . the market is nearly three times as high as it was then, and even the bracing plunges of the last two trading days comprised only a 4.3 percent drop in values, where the 508-point drop of October 19,1987 represented a 22.6 percent drop (to 1,738.74). As Alan Greenspan has all too famously noted, the market has a little air in it. Watch for Friday s Labor Department report to see just how skittish investors have become. A stronger-than-expected showing could set off another Wall Street jolt fearing further interest rate increases by the Fed. For investors, the skinny remains: don't panic. Good news is still good news, and the economy, after all, is strong. But as snow fell Monday on downtown New York, the traders in Wall Street s vaulted warrens continued to usher March out like a polar bear.