The Bombay Stock Exchange benchmark Sensex opened over 61 points higher today on the back of selective buying by funds and retail investors. The 30-share index, which had lost 45 points in the previous session, rose by 61 points, or 0.30 per cent, to 20,090 points in the first few minutes of trade.Likewise, the wide-based National Stock Exchange Nifty index moved up by 13 points, or 0.21 per cent, to 6,011 points.Brokers said the buying activity was mostly confined to metal, consumer durables, power and information technology stocks. They said trading volumes were low on account of poor participation by foreign funds on account of the end-of-year holidays.