Rising Brexit fears prompted a huge outflow from UK equity funds in the week to Thursday.
Data compiled by Bank of America shows that nervous investors withdrew $1.1bn (£769m) during this period, which marks the second largest outflows in the past decade behind last year's nail-biting General Election.
Uncertainty ahead of the EU referendum on 23 June has been rippling through financial markets. Bank of American said traders are increasingly favouring safe assets such as gold, US bonds and the Japanese yen.
"June thus far has been all about the risk-off Brexit trade," it said in a note.
Shares, oil prices and bond yields rose as campaigning was suspended following the tragic death of MP Jo Cox. They reversed earlier losses this week which came after opinion polls showed a swing towards the Leave camp.
Cox was stabbed and shot by a man on the steps of her constituency surgery yesterday. Numerous politicians, including leaders across Europe and the rest of the world, have since paid tribute to the murdered MP.