The Sensex at the Bombay Stock Exchange lost 70 points to 18,440 in late morning deals, due to sustained selling by funds despite a rally in sugar companies' stocks. Earlier, the 30-share BSE benchmark index, which had lost 531 points in the past two sessions, lost 0.25 per cent, to 18,463 in the early trade.The Nifty, at the National Stock Exchange declined by 24 points to 5,552.