Swiss bank UBS reckons the operational impact of a Brexit would be "minimal" for UK-listed asset managers.

In a research note to clients on Tuesday, analyst Michael Werner said UK fund houses would need to re-register or re-domicile 8% or less of their outstanding assets under management in a Brexit scenario.

Most London-listed fund managers have fund platforms outside the UK (usually in Luxembourg or Ireland) which would "likely mitigate the operational risk" if the UK decides to leave the EU in June, according to the analyst.

"We view the ultimate operational impact to the listed UK asset managers of a Brexit scenario where financial passporting is banned as small," he said.

The house view at UBS is that Aberdeen Asset Management and Henderson have the largest operational risks should a Brexit occur.

The investment bank calculates that 7-8% of Aberdeen and Henderson's AUM base could require a re-registration of investment funds in the event of the UK leaving the EU.

Although both firms have fund platforms in the UK and Luxembourg, so UBS does not expect the costs of re-registering/re-domiciling certain funds to be onerous.

For Schroders, UBS' Werner estimates just 1.5% of its AUM base would require re-registration.

Smaller UK asset managers are likely to be hit hardest by a Brexit, he reckons, as they are more likely to rely on passporting as a way to distribute UK-domiciled funds into continental Europe. or vice versa.

“Due to the smaller scale of these asset managers, they are less likely to have separate fund platforms in both the UK and the EU, which would provide the larger asset managers operational risk protection from a Brexit," he said.

UBS adds that it would view any share price declines, particularly at Schroders, as the UK Brexit referendum nears as attractive entry points for investors.

“Given the minimal impact that we expect Brexit to have on the large, listed UK asset managers from an operational perspective, we believe any uncertainty can create investment opportunities for investors.”