In another day of light August trading, the S&P hit 1,426.68, its highest intraday rise since May 2008.
The index has gradually edged up over the last fortnight – a trend described by some analysts as a rally in slow motion.
Only three of the past 12 sessions have seen moves of 0.25 per cent or more by the S&P.
Some energy stocks initially lifted shares on the S&P, along with an ongoing bullish attitude among investors that European Central Bank chief Mario Draghi’s pledge to do “whatever it takes” to save the Eurozone will soon come to fruition.
Yet by the close of play the S&P had dropped 4.96 points, or 0.35 per cent, to end at 1,413.17.
While many investors remain optimistic over prospects in the Eurozone, and growth in the US, the risk of shocks still hangs over the world’s number one economy.
Capital Economics released its latest outlook for the American economy last night, warning that “downside risks abound”.