Erasing its initial gains, the Sensex at the Bombay Stock Exchange was trading 80 points in the negative territory at 20,411 in late morning trade, when reports last came in. The 30-share index had opened 93 points in the green, on fresh buying by funds and retailers, ahead of industrial output data. It had lost over 748 points in the previous five sessions.The Nifty at the National Stock Exchange was trading 20 points in the red to 6,059.