Mumbai:  In thin trading, BSE benchmark Sensex on Thursday ended 21 points lower, dragged mainly down by HDFC Bank, Hero MotoCorp, Bajaj Auto that fell in the range of 1-3 per cent.

The 30-share Sensex, which had lost 56 points in the previous session, fell by 20.62, or 0.12 per cent to 17,130.67 points.

On Tuesday, S&P lowered the sovereign credit outlook from stable to negative on risks from slower economic growth and a widening budget deficit.

Brokers said the falling trend was also influenced by factors such as funds cutting their pending positions as derivatives for April series expired and a weak opening in European stock markets.

They also said that with the expiry in the derivatives segment, buying activity almost dried up and reduced the trading volumes to an extent.

The 50-share National Stock Exchange index Nifty fell by 13 points, or 0.25 per cent to 5,189 as stocks of power and realty sectors suffered losses.

Major losers in Sensex that have lost over three per cent fall include Hero MotoCorp, Bajaj Auto, Tata Motors, Maruti Suzuki, GAIL India, Hindalco, DLF Ltd., Tata Power, NTPC, Bharti Airtel, State Bank of India and Sterlite Industries.

However, the two most influential stocks on the index with  nearly 20 per cent combined weightage ended higher today. Reliance Industries gained 1.24 per cent to Rs 745.45 and
Infosys closed 0.40 per cent up at Rs 2,358.20, cushioning the down-trend.