ZURICH (Reuters) - Swiss asset manager GAM Holding AG could cut more than 40% of its workforce as Chief Executive Peter Sanderson seeks to restore profitability at the group, Bloomberg reported on Monday citing an unidentified source.GAM declined to comment on the report, which said the company could reduce employee numbers by between 250 and 350 under one scenario being discussed. It employed 863 staff at mid-year, down from 935 full-time equivalents a year earlier as it slashed costs.No..