The Switzerland-listed asset management group warns that lower performance fees will likely dampen profits in the first half.

GAM's underlying profit before and after tax in the first half of 2016 is expected to be around 50 per cent lower than a year ago, the group said in a statement.

The post-tax IFRS profit reported for the first half of 2015 was SFr80.9 million ($83.9 million), while underlying pre-tax profit for the same period totalled SFr101.5 million.

The Zurich-headquartered group attributed the expected decline largely to a plunge in performance fees, which are expected to be around SFr1 million, a sharp drop from the SFr44.1 million reported for the first half of 2015. GAM first warned performance fees would likely be hit in April in its first-quarter statement, which revealed a 4 per cent drop in assets under management to SFr114.7 billion.

Net management fees and commissions are also expected to decline, mainly due to lower average assets under management and a slight narrowing of the average management fee margin.

GAM, which last month agreed to acquire UK-based equity investment firm Taube Hodson Stonex, will report its half-year results on 3 August 2016.