Clients stepped up withdrawals from Grupo BTG Pactual SA’s money management unit on Thursday, according to a source with knowledge of the bank’s strategy, as Latin America’s largest independent investment bank tries to contain fallout from the arrest of its top executive. Outflows reached a cumulative 3.5 percent of assets under management over the past two days, the source said. Redemptions had hit around 1 percent on Wednesday, when Chief Executive Officer André Esteves was arrested on suspicion of obstructing a sweeping corruption investigation.