The S&P 500 held yesterday's lows and that initially led to some bottom picking but those gains are accelerating now and the S&P 500 is up 68 points, or 1.2%.

SPX
SPX 5 mins

There is some talk of progress on the Congressional tax cut package and that could be helping but I think this is mostly about hopes that North American tariffs are lowered.

Source: Forex Live