Disillusionment with investment products and returns is prompting well-to-do Asians to take greater control of their wealth. That's a vexing development for several global wealth management firms that have made big bets on expanding in the region, now home to more millionaires than North America. Managers at HSBC Holdings, UBS, Citigroup, and other banks catering to high net worth clients in Asia have full discretion over their portfolios for just 4% of assets under management, according to a June report from Boston Consulting Group. Asia's wealthy lost a lot of trust in their private banks and private bankers during the 2008 financial crisis, says Peter Damisch, a BCG partner who co-authored the report. This partially explains why profits are shrinking at some wealth management firms.