Aberdeen Asset Management chief executive Martin Gilbert said financial services firms should avoid “knee jerk reactions” to the vote, despite world stock markets plunging yesterday.
In London, more than £50billion was wiped off the value of the UK’s biggest companies following the Brexit result.
The FTSE 100 Index closed down 3.15%, falling 199.41 points to 6,138.69, while the FTSE 250 slid 7%, or 245.5 points to 16,088.1.
Germany’s Dax index was 6.8% off and the Cac 40 in France was down 7.9% as both markets pulled back from 9% falls in earlier trading.
The US Dow Jones Industrial Average opened 2.8% lower, before paring back to a drop of 2.5% as the FTSE 100 closed.
Mr Gilbert said: “Whilst some of the market falls are steep, from my long experience having worked through Black Monday, Black Wednesday, the Asian crisis, etc this is not the time for knee-jerk reactions but rather it’s important to have a calm head on behalf of our clients.
“As long-term investors, often the best course of action is to do nothing or even take advantage of mis-pricing opportunities.
“Despite the result, nothing has changed today. The UK is still a member of the EU and the same laws and regulation continue to govern the financial services sector.
“Importantly consumer rights and protections are also unaffected. In the days, weeks, months to come a clearer picture will emerge but I have no doubt that asset managers may need to and will be able to adapt.”
The London market resembled a sea of red, with heavyweight financial stocks and travel firms falling sharply.
Brent oil prices also took a tumble, dropping 4.1% or $2.11 to $48.80 a barrel in the wake of the Brexit decision.