The Dow celebrated Columbus Day with a 936.42-point gain today, leaping an astonishing 11.1 percent to 9,387.61. The index's biggest ever one-day point gain snapped an eight-day losing streak described by The Wall Street Journal as "brutal" and came amid new international actions to shore up a teetering global economy. European and Asian markets also rebounded on a day that 29 of 30 Dow components posted gains, with General Electric the lone loser. Despite the colossal rally, many Wall Street veterans expect further economic thunderclouds over the next few months. "The danger here is that people will be lulled into the idea that a strong bull trend is now in place rather than the idea that the market is just bouncing off a short-term oversold condition," Michael Darda, chief economist at MKM Partners, a trading and research firm in Greenwich, Conn., told The Journal.