Total investor wealth of BSE-listed companies plummeted by Rs 2,26,179.25 crore to Rs 1,01,00,507 crore.
The Sensex plunged 660.61 points or 2.37 per cent to settle at 27,188.38 after forecast of deficient monsoon and cautious stance of RBI on economic recovery.
This is the index's biggest single-day fall in almost a month.
Among the 30-Sensex stocks, 29 ended with losses led by State Bank of India, AXIS Bank, Hindalco Industries and ITC.
Bharti Airtel was the lone gainer among Sensex blue-chips.
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At the BSE, 804 stocks advanced, while 1,875 declined. 103 stocks remained unchanged.
"Equity benchmarks witnessed steep decline after RBI took a cautious stance on economic recovery even as it cut the policy rates by 25 basis points. Adding to pessimism, Indian Met Department's latest report on monsoon further dampened the sentiments.
"As a result, selling pressure was witnessed across the board but rate sensitive sectors lost maximum amongst all," said Jayant Manglik, President-retail distribution, Religare Securities Limited.
Monsoon in the country this year is expected to be "deficient", the Met department has projected while revising its forecast from "below normal" which is likely to trigger fears of a drought.
RBI cut the repo rate (short-term lending rate) from 7.5 per cent to 7.25, but left all other policy tools like cash reserve requirement unchanged at 4 per cent and Statutory Liquidity Ratio (SLR) at 21.5 per cent.
"Policy announcement by RBI was at par with the expectations of D-Street. But markets were in a bad mood post policy announcement as the news was already discounted," said Rohit Gadia, Founder & CEO, CapitalVia Global Research Ltd.