Wall Street’s five-day losing streak came to a merciful end this afternoon, with the Dow gaining 149.82 points, or 2.2 percent, to close at 6,875.84. Propelling the positive momentum were hopes for a new stimulus package in China, as traders snapped up industrial and commodities stocks. Caterpillar, a major exporter to China, climbed 13 percent, as did Alcoa. China fever also spurred a 2.4 percent rise in the S&P 500 and a 2.5 jump for the Nasdaq. But don’t get too giddy: Analysts are warning that today’s rally is nothing but a blip in a bearish season.