As people change jobs more frequently, or lose them or retire, mutual-fund companies risk losing their accumulated 401(k) assets from the plans they have managed since the 1990s. Many employees roll their 401(k)s into IRAs when they leave jobs, and a new Morgan Stanley study shows that only about one in five such rollovers stay with the same investment provider; study author Henry H. McVey points out that mutual-fund companies are not set up to retain retirement money when employees roll the funds over. But the rollover IRA market is too big for the fund companies to ignore--Vanguard Group has built a unit over the past two years to handle money moving out of 401(k)s, and its representatives discuss options for people leaving Vanguard 401(k) plans, including rolling the money into a Vanguard IRA. McVey also notes that even if an employee moves money from a 401(k) managed by a fund company to a securities firm account, the money may eventually be invested in some of the fund firm's products.