Mumbai: The BSE benchmark Sensex failed to maintain last week's gains and slipped 284 points due to fresh selling pressure, mainly in refinery, banking, realty, metal and auto counters, in view of persistent capital outflows from foreign funds.

The Bombay Stock Exchange 30-share barometer resumed up at 15,782.77 and immediately hit a high of 16,049.12, but ended the week at 15,454.92, showing a net loss of 283.78 points, or 1.80 per cent, from its last weekend's level.

During 2011, the Sensex has tumbled 5,054.17 points, or 24.64 per cent, eroding Rs 20 lakh crore in investor wealth.

The 50-issue index Nifty of the National Stock Exchange also dropped 89.70 points, or 1.90 per cent, to end the week at 4,624.30. The index tumbled 1,510.20 points, or 24.62 per cent, during the year.

Sensex moved between the positive and the negative terrain throughout the week in view of volatility as traders rolled over positions in futures & options (F&O) segment from the near-month Dec 2011 series to Jan 2012 series.

Amid lack of any major trigger from the overseas markets due to Christmas holidays, operators preferred to book profits at the fag end, leading to fall.

Top heavyweight RIL was the major contributer to the Sensex fall on reports that gas output from the petro-chem giant's eastern offshore KG-D6 gas field declined to a fresh low during the week ended December 18.