After opening higher, the BSE benchmark Sensex on Friday slipped by 136 points to trade at 18,548.54 at 1015 hrs with selling pressing emerging in realty, auto and capital goods sector stocks.

Similarly, the broad-based National Stock Exchange index Nifty fell by 47.85 points, or 0.85 per cent, to 5,556.45.

The 30-share index opened the day higher by 36.44 points, or 0.19 per cent, to 18,720.87 points.

Marketmen said a weak trend on Asian bourses dampened the sentiment in Mumbai and triggered widespread selling.

Investors were also concerned over rising food inflation and a hike in key interest rates by the Reserve Bank of India, they added.

Food inflation inched up marginally to 15.57 per cent for the period ended 15th January, on account of escalating vegetable prices, particularly, onions.