Stock Market Today: Domestic headline indices started the session on May 23 on a flat note, tracking US market indices. The Sensex opened 54.99 points or 0.07 per cent lower at 80,897, while the Nifty 50 started 29.80 points or 0.12 per cent higher at 24,639.50. However, a few minutes into the trade, Sensex rose as much as 250 odd points to reclaim 81,200 level, and Nifty 50 surged over 110 odd points to trade above 23,700 level.