The filing last Friday of insider trading and conspiracy charges against top officials of the Galleon and New Castle hedge funds raise anxious questions for those funds' investors, writes Brooke Masters, chief regulation correspondent .

US regulators and prosecutors allege that managers at both funds relied on improper use of non-public information to beef up returns and are suing to force the disgorgement of $20m (€13.4m, £12.2m) in profits, plus penalties.