By 9:30 a.m., the Sensex had reversed course, falling 200 points, or 0.23%, to 83678.17, while the Nifty 50 went past the 25,700 level, as investors turned cautious after the opening uptick.On the 30-stock Sensex, gains were led by Tech Mahindra, IT stocks outperformed, with the index rising 0.6%. The advance was broad-based, with small-cap and mid-cap indices each adding about 0.4%.Live EventsIn the previous session, both the Sensex and the Nifty rose roughly 0.4% as expectations built that India-U.S. tra ...