A group of much-hyped finance startups made a big bet on millennials -- but it won't work

America's deep-rooted wealth management sector has been feeling an uneasy rumbling underfoot of late. The threat: a group of tech-savvy underdogs aiming squarely at millennials. Robo-advisers such as Betterment, FutureAdvisor and Wealthfront have been attracting attention and assets, pitching themselves as low-cost and convenient alternative to brokerages. Some have said their assets under management could grow 68% annually, reaching $2.2 trillion by 2020. But according to a new report...