The BSE benchmark index Sensex gained over 100 points in opening trade today, continuing its winning streak for the fourth day, on buying by funds and retail investors. Firming trends at other Asian bourses also influenced the trading sentiments. The 30-share Bombay Stock Exchange index rose by 108 points to 16,268 points in opening trade. The barometer had surged by over 752 points in the past three sessions. The wide-based National Stock Exchange index Nifty rose by 31.95 points to 4,828.10 points. Brokers said sentiments on the domestic bourses were buoyed after the Prime Minister promised a gradual but steady push to financial sector reforms.