Mumbai: The BSE benchmark Sensex broke its seven-week long winning spree by tumbling 366 points to finish below the 18,000 mark due to profit booking from operators and investors in view of concerns over rising crude oil prices and higher fiscal deficit.

This was the first weekly fall posted by the 30-share index since the beginning of the current calendar year.

Selling pressure was mainly seen in realty, banking, capital goods, metal, power and auto sectors. Second-line stocks also underperformed the Sensex on profit booking by retail participants.

Higher oil prices spooked investors sentiment as rise in prices could worsen a widening trade deficit and also weigh heavily on inflation.

India's fiscal deficit is expected to be 5.6 percent of Gross Domestic Product (GDP) this fiscal as against the budget estimates of 4.6 percent.

Planning Commission Deputy Chairman Montek Singh Ahluwalia expressed concern over the mounting current account deficit at an ASSOCHAM conference.

The Sensex hovered in range of 18,523.78 and 17,848.93 before ending the week at 17,923.57, showing a net fall of 365.78 points, or 2.00 percent, from its last weekend's level. The key index had gained by a massive 2,834.43 points, or 18.34 percent, in the last seven weeks.

The NSE 50-share Nifty also dropped by 135.00 points, or 2.43 percent, to finish at 5,429.30. It had gained a whopping 940.00 points, or 20.33 percent, since the beginning of this year.