The index could not hold the gains and fell sharply in late noon deals to touch a day's low of 15,526 - down 445 points from day's high.
The Sensex finally ended (provisional) with loss of 204 points at 15,566.
The market breadth was negative - out of 2,716 stocks traded, 1,516 declined, 1,132 advanced and 68 were unchanged today.
The NSE Nifty ended (provisional) with a loss of 50 points at 4,620.