Wall Street gains as weak dollar boosts commodities

Profits at S&P 500 companies are expected to have fallen 7.7 percent on average in the first quarter, according to Thomson Reuters I/B/E/S, under pressure from a weak global economy. Alcoa , seen as the unofficial start to quarterly earnings season, is set to post first-quarter results after the market closes. Crude oil, which has been a big influence on the stock market this year, was up more than 2 percent ahead of next Sunday's meeting of producers aimed at freezing output.