The U.S. stocks ended the worst January since 2009 with the best one-day gains in more than four months, after earnings from Microsoft Corp. exceeded expectations and the Bank of Japan stepped up monetary stimulus.

Equity gains accelerated in the final hour, with the strong finish a fitting end to a weak month that featured sharp reversals on an almost daily basis. Microsoft led the surge Friday with its biggest gain in three months. Nine of the S&P 500’s 10 main groups rose at least 1.6 percent. Amazon.com Inc. was a blemish, tumbling 7.6 percent as earnings for the holiday quarter missed estimates.

S & P 500 rose 2.5 percent to 1,939.72 at 4 p.m. in New York. The gauge slumped 5.1 percent in January, its worst start to a year since the height of the financial crisis.

Stocks swung between gains and losses this week as investors assessed corporate earnings and the degree to which central banks will intervene to help stem increasing volatility and a dimming outlook for global growth.

Prior to today’s unexpected action from the Bank of Japan to adopt a negative interest-rate strategy, the European Central Bank signaled last week it could boost stimulus as soon as March. The Federal Reserve said Wednesday it was watching to see how the global economy and markets impact the U.S. outlook.

Source : Bloomberg