Contrary to the advice of retirement experts, employees at some of the largest U.S. corporations have as much as 70 percent of their retirement savings invested in company stock, according to David Blanchett, head of retirement research at Morningstar Investment Management.
Ideally, employees' 401(k)s should not include any of their own company's stock, says Blanchett. The risk, he says, is to the employee and the company alike.
(Read more: Record 401(k) Balances—How Does Yours Compare?)
"The last thing you want to have happen is to encourage your employees to buy your company stock in their 401(k) and have it drop 40 to 50 percent, so I think the liability there is for the companies that offer it," Blanchett explained on CNBC's "Power Lunch."