"The target-date approach was tested in the 2008 financial crisis, and many investors were surprised by the declines in their funds. For example, funds with a 2010 target date lost 30% on average in 2008, with losses ranging as high as 41%, [SEC commissioner] Luis A. Aguilar said in a speech to a retirement-planning summit in Washington last month.... 'The relentless growth in target-date funds is troubling because studies have shown that investors and industry professionals alike do not fully appreciate the risk these funds present,' Mr. Aguilar said. He cited as one example a 2012 study, sponsored by the SEC, on investors' understanding of target-date funds. It found only 36% of respondents were aware that these funds don't provide guaranteed income after retirement."