(Reuters) - Wall Street's main indexes jumped at the open on Thursday, with the S&P 500 notching an intraday record high after the Federal Reserve kicked off its easing cycle with half-a-percentage point reduction and forecast more cuts were on the horizon.

The Dow Jones Industrial Average rose 469.5 points, or 1.13%, at the open to 41972.56. The S&P 500 rose 84.4 points, or 1.50%, at the open to 5702.63​, while the Nasdaq Composite rose 407.6 points, or 2.32%, to 17980.891 at the opening bell.