Mirroring mixed cues from the global markets, the Sensex opened marginally (20 points) lower at 13,139, and swung in and out of the positive zone in early trades.

Aggressive buying in cement, metal and select auto stocks helped the index flare up to a high of 13,254 - up 95 points from its previous close.

However, persistent selling in heavyweights ITC, Reliance, TCS and SBI dragged the index into the negative zone. The selling intensified in late noon trades, and the index plunged to a low of 12,837 - down 417 points from the day's high.

Eventually, the  index ended with a significant loss of over 2% (273 points) at 12,886. In the process, the Sensex today completed third straight week of losses, and has shed 11.4% (1,653 points) during the period.