The S&P jumped to 2,117 points in late-morning trading in New York. That was after the Dow Jones edged to 18,001 points - although it later fell back.
Global equities have been hit by volatile trading in recent months. In mid-April, the Dow Jones went as high as 18,096 points, before falling again on weak oil prices and global uncertainty.
On Friday it fell as low as 17,705 points after the US Bureau of Labor Statistics posted disappointing non-farm payroll figures. The news also sent the dollar into a spin, falling almost 1.5 per cent against the euro.
But in a speech yesterday Federal Reserve chair Janet Yellen sought to quell fears, saying that though the figures were "concerning" she remained "cautiously optimistic" over the state of the economy, adding that "positive economic forces have outweighed the negative".