Swiss bank UBS AG
Switzerland's biggest bank in a statement rejected as damaging and untrue media reports about Ermotti's private board membership mandates, saying it had in fact approved them.
In his new role as the CEO of UBS, which requires his full attention, Sergio Ermotti will hand over all of his private mandates in a quick but orderly manner, UBS said.
Several Swiss newspapers had reported in the past week on Ermotti's business dealings apart from UBS.
The UBS board of directors accepted on Saturday the resignation of German-born chief executive Gruebel, 67, after its scandal-hit investment bank lost $2.3 billion in alleged rogue trading.
The board appointed Ermotti, who hails from Switzerland's Italian-speaking region of Ticino, on an interim basis.
Ermotti pursued various business interests in Lugano, including as president of Lugano-based Darwin Airlines. He was also a co-owner of a chain of luxury hotels.
To aid its search for a permanent successor, UBS has hired head-hunting firm Egon Zehnder International and also approached former JP Morgan Chase & Co
Egon Zehnder International was not immediately available for comment. Both UBS and Bill Winters also declined to comment.
Chairman Kaspar Villiger has said Ermotti, already being groomed as a possible successor since he joined UBS from UniCredit SpA
(Reporting by Catherine Bosley; additional reporting by Steve Slater in London; editing by Matthew Lewis and Andre Grenon)