"The combination of political instability in the UK, political uncertainty across Europe, and a messy withdrawal process would exacerbate the impact of a vote to leave on financial markets. The signals are already there with sterling under pressure and gilt yields and equity prices falling as the opinion polls have narrowed… Looking beyond the macro data the most immediate and tangible signs that Brexit would have structural implications for the UK economy would be from direct investment decisions," the report said.
The report added that the firm did not expect that major companies would make any "hard-to-reverse decisions precipitously," but Brexit several high-profile investment decisions would certainly be affected.
On Thursday, voters across the United Kingdom will take part in a referendum to decide whether or not the country should exit the European Union.