The company suspended Tim Haywood, investment director business unit head for the unconstrained/absolute return bond strategy (“ARBF”), following the probe.
The firm pointed out that the investigation had “not raised concerns regarding his honesty” and said the “relevant regulators are being kept informed of the matter.”
GAM has not established any material client detriment to date as a result of the issues investigated, although this remains under review.
London-based Mr Haywood joined GAM following its acquisition of the fixed income and foreign exchange firm, Augustus, in May 2009.
Before Augustus he worked at Orient Overseas International Limited in Hong Kong, where he was chief investment officer.
Jack Flaherty and Alex McKnight, investment directors, have now assumed joint responsibility for the ARBF and other associated portfolios.
Jack Flaherty has been one of the co-managers of the ARBF strategy for more than six years, while Alex McKnight has been a member of the ARBF team for the past 11 years.
Group chief executive, Alexander S. Friedman, said: “We take our responsibilities and controls very seriously.
“Having conducted the investigation with external counsel, we now intend to follow our usual internal processes and will take any further action that may be appropriate.
“GAM is a leader in the absolute return bond category, and has been for many years.
“We are fully committed to remaining so.”
Subsequently, following Mr Haywood’s suspension, the firm said it had “experienced a high level of redemption requests” and all subscriptions and redemptions in its unconstrained/absolute return bond funds (ARBF) were suspended.
The company said its fund boards were “considering all future steps, including fund liquidations, to maximise value and liquidity for clients.”
Chairman, Hugh Scott-Barrett, said: “The board of directors acknowledges that recent events have been a setback for the company.
“However, we have absolute confidence in the strength of GAM as a diversified asset manager and the ability of its investment teams to deliver returns for clients.
“We have a clear strategy and management will continue to execute against it.”