Mergermarket's "Global and regional M&A: H1 2016" report showed merger and acquisition activity value in the U.K. dropped 50.5 percent on-quarter in the April - June period to $19.3 billion from $38.9 billion.
"Firms postponed deals, cautious of the impact [on] exchange rates and questioning what they will actually be buying into, unaware of how future negotiations will affect them," the report said.
On June 23, the U.K. voted to quit the EU that prompted many international organizations and investment banks to reduce their growth forecast for Britain. Rating agencies have also downgraded the U.K.'s credit ratings.
The British pound dropped to 31-year lows in the immediate aftermath of the vote before recovering slightly.