London - The FTSE 100 fell more than 8 percent at the open, wiping more than 100 billion pounds ($136.7 billion) off the market cap of the UK's biggest blue chips after the country voted to leave the European Union.
Following the result, British Prime Minister David Cameron said he would resign.
The blue-chip FTSE 100 index was down by around 7 percent in early session trading, its worst one-day percentage loss since October 2008, when global markets slumped in the wake of the collapse of Lehman Brothers.
The mid-cap FTSE 250 index, which is dominated by companies exposed to the domestic British economy, also fell 11.4 percent.
Among the hardest hit stocks were banks, housebuilders and property companies.
Financial services group St James's Place fell 29 percent while housebuilder Barratt Developments slid 26 percent.
REUTERS