The deal, which has already encountered a number of regulatory and governance hurdles, would see UniCredit’s Pioneer Investments merged with Santander Asset Management.
At a meeting in Milan on Tuesday, however, UniCredit advised that chief executive Federico Ghizzoni acknowledged that a change was needed to the company’s management structure and “expressed his willingness to work with the chairman to find an agreement to terminate his contract”.
Ghizzoni has agreed to stay in office until his successor has been appointed.
There is concern, however, that a new UniCredit chief executive could scupper the agreement, reports Reuters, citing four sources close to events.
“There is a high chance the Santander deal with be called off,” one source said, adding that there is a queue of other buyers for Pioneer.
One of Europe’s biggest fund groups
The deal, first announced in April 2015, would create one of Europe’s biggest fund groups.
Valued at around €5.4bn (£4.1bn, $6bn) last year, the merged firms would create a holding company named Pioneer Investments, which would have combined assets under management of around €400bn.
Under the terms of the preliminary agreement, a holding company named Pioneer Investments is to be created, which will control Pioneer's US operations along with the combination of Pioneer and SAM's operations outside the US.
UniCredit and private equity firms Warburg Pincus and General Atlantic will each own 50% of the holding company, which will in turn own 100% of Pioneer US, and 66.7% of the combination of Pioneer and SAM's operations outside the US, while Santander will directly own the remaining 33.3% stake.
The combined firm will continue to operate as one global entity, led by a single global management team, focusing on meeting the needs of its clients worldwide.