Headline indices opened with marginal gains on May 15. However, they immediately slipped into the red, mostly weighed down by banks. The Sensex started 23.87 points or 0.03 per cent higher at 81,354.43. As of 9:20 AM, it traded some 200 odd points lower. Likewise, the Nifty 50 opened with slight gains of 27.55 points or 0.11 per cent at 24,694.45, and slumped to trade some 50 odd points lower.