The Dow Jones Industrial Average and the S&P 500 index rallied to trade at session highs late Monday afternoon, with the benchmarks on track to post their sharpest one-day climb since Aug. 26, 2015, according to FactSet data. The Dow DJIA, +2.84% was up about 611 points, or 2.56, at 24,147. Meanwhile, the S&P 500 index SPX, +2.72% was trading up 62 points, or 2.4%, at 2,650, also on track for the best daily rise since late August of 2015. A cooling of tensions around trade between the U.S. and China has given way to a powerful rally for U.S. stocks, which are coming off the worst weekly decline in more than two years. Meanwhile, the Nasdaq Composite Index COMP, +3.26% surged 2.8% to 7,196, also putting the technology-heavy index on pace for its best one-session gain in about 2 1/2 years, on a percentage basis.