GAM has seen its assets under management increase to CHF148.4bn (£114.79bn).
This is up 13 per cent during the three-month period to the end of September.
The figures, released this morning (19 October) in its interim management statement, also showed its assets were up 23 per cent during the first nine months of 2017.
Alexander Friedman, chief executive of GAM, said this was driven by strong net inflows, positive investment performance and foreign exchange movements.
He said: “I am pleased with our continued momentum in the third quarter: the investment performance for the vast majority of our funds was strong, our net inflows were very good, and we remain on track with our strategic initiatives.
“We continue to see healthy client interest for our products, although we do not expect the pace of third-quarter inflows to be consistently maintained.
“Our focus remains on providing excellent investment performance in differentiated strategies that meet our clients' needs, disciplined execution of our growth strategy and ensuring we make GAM as efficient as possible.”
The data showed its investment performance improving, with 75 per cent of investment management assets in funds outperforming their respective benchmark over the three-year period to 30 September 2017.
Over the five-year period, 72 per cent of assets in funds were outperforming.
Absolute return strategies had net outflows of CHF0.6bn (£0.46bn) and in fixed income net inflows totalled CHF4.1bn (£3.17bn).
In equities, net inflows totalled CHF0.1bn (£0.08bn) while systematic strategies saw net inflows of CHF0.1bn (£0.08bn).
Multi asset strategies saw net outflows of CHF0.1bn (£0.08bn).
The news comes as GAM hired Adrian Gosden, the former Artemis Income co-manager, as investment director.
GAM also strengthened its distribution division with the hiring of Shizu Kishimoto to lead its sales and business operations in Japan.
The company also announced it would follow many of its peers in absorbing research costs in line with incoming Mifid II rules to make them explicit.