By Russell Hotten
By Mary-Ann Russon
Business reporter, BBC News
Us markets have followed Europe and Asia down.
The S&P 500 has fallen 5.21% to 2,397.79, while Dow Jones is down 5.22% at 20,129.70.
The Nasdaq has lost 4.33% to drop to 7,017.38.
The S&P 500 has lost some of its earlier gains but is still up 4.08% on the day at 2,483.58.
The Nasdaq index is up a simialr amount - 4.11% - at 7,188.23.
The Dow Jones is up 2.35% at 20,662.91.
US stocks have been in a much more positive mood today.
The S&P 500 is currently up 51.35 points or 2.15%, 2,437.48.
The Dow Jones index had a positive opening but has fallen back a bit now
It's at 20,211.15, up 22.63 points or 0.11%.
The Nasdaq is at 7,002.02, up 97.43 points, or 1.41%.