The Institute of Management and Administration's (IOMA) latest study indicates that 27.9 percent of 401(k) plan stocks are invested in employer stock, despite recent media attention on corporate scandals and advice from financial planners and some employers to diversify. The group attributes the trend to many employers' stock outperforming those listed in Standard & Poor's (S&P) 500 index, which fell 19.5 percent compared with 327 companies' stock that only fell 12.1 percent. Moreover, companies like United Airlines have employees who are expecting a rebound, and who feel slighted if they are forced to dump their company shares. IOMA also indicated that while some companies have eliminated many of their trading restrictions, some have still clung to age and tenure restrictions regarding the sale of matching contributions. IOMA's study noted that 13 plans have 75 percent or more of their assets in company stock, and an additional 54 plans have 50 percent or more of their assets in employer stock. Vanguard Group Managing Director William McNabb stated, "It's vital to be diversified," and many financial experts agree that having over 5 percent or 10 percent of 401(k) assets in one stock is too risky. However, Hewitt Associates discovered that 83 percent of 200 companies have made diversification a top priority in retirement savings education for employees.