Funds managed by BlackRock and JO Hambros have been selling their stakes in rival firm Liontrust since the latter announced its plan to acquire Neptune.
Data released to the stock exchange in recent weeks shows funds managed by BlackRock have, in a series of transactions, reduced their holding in Liontrust from 11.26 per cent to 10.14 per cent.
BlackRock funds owned over 12 per cent as recently as July.
The shares are held in the BlackRock Smaller Companies investment trust, run by Roland Arnold. Mr Arnold took over as manager in May 2019.
A stock market filing shows rival fund house JO Hambro also trimmed its stake in Liontrust to 4.99 per cent from the previous 5.01 per cent.
Those sales have all happened since Liontrust confirmed its agreement to buy Neptune on July 31.
Liontrust is paying £40m for Neptune.
The shares of the fund manager have risen steeply since June, from £6.50 to £7.68.
At the end of March 2019 the company had assets under management of £12.7bn. Assets under management were boosted by inflows into the companies range of bond funds, launched following the hiring of bond managers from Kames and Baillie Gifford.