Millennials Are Pretty Cocky About Their Investing Skills

The results suggest the generations are reacting very differently to market fallout from the U.K.'s vote to leave the European Union, says David Kuplic, Securian's chief investment officer and executive vice president at its subsidiary Advantus Capital Management. "The boomers are going to be much more likely to hold on," Kuplic says. "I think the millennials will be more active." That could mean both selling out of fear, or buying on "the belief that a market correction is an opportunity."

Market downturns can indeed be opportunities, especially if you still have decades left before retirement. When asked how they'd typically react to a falling market, some 24% of millennials and 19% of boomers said they'd buy more stock. But the two groups were very different in their willingness to ride out a crisis, as many experts advise. Almost three out of five boomers said they'd make no change to their portfolios, while only 37% of millennials said the same. And young people were far more likely to say they'd sell into a falling market—a move that can lock in losses. About 16% of millennials said they'd sell when the market fell, compared with only 1.6% of boomers.

Some nasty experiences (in 2008, for example) have taught boomers the dangers of panicking when markets fall. They've also learned to be humble. Sometimes the best decision to make in a crisis is no decision at all. Pride, the millennials may find, comes before a fall.

— Check out 401(k) Participation Up 19% From 2011: Wells Fargo on ThinkAdvisor.