U.S. stocks ended the day mixed, but managed to score a blockbuster March. The S&P 500 closed the month with a gain of nearly 7 percent, its best monthly performance since October. Crude is up more than 13 percent for the month and has risen nearly 4 percent for the quarter. Negotiations for a production cap among OPEC members and some signs of slowing domestic output propelled commodities higher through March. McDonald's (MCD) - Get Report plans for a big push into China, targeting 1,250 new restaurant openings in the region over the next five years. CEO Steve Easterbrook said Asia was a 'significant area of opportunity.' Rio Tinto (RIO) - Get Report has been cut to SELL from HOLD at Axiom Capital. Analysts said poor performance in copper and aluminum prices have increased the risk of reduced earnings. TheStreet's Keris Lahiff reports from Wall Street.