The BSE benchmark Sensex today fell by over 135 points to 18, 783 in early trade as funds and retail investors booked profits after recovery in the previous session amid a mixed trend in the Asian region.The 30-share barometer, which gained 56.98 points in the previous session on Friday, moved down by 135 points, to 18,783, led by the weakness metals, capital goods, power and banking sector stocks.Similarly, the wide-based National Stock Exchange index Nifty, moved down 46 points, to 5,672.