With 401(k) retirement plans, both the employer and the employee make contributions that are then invested, typically in mutual funds. A column in the Wall Street Journal describing these plans notes: “Vesting is the amount of time you must work for your company before gaining access to its payments to your 401(k). (Your payments, on the other hand, vest immediately.)” Why do 401(k) plans have vesting periods for the employer’s contributions? Do vesting periods have any advantages to employees relative to a system without vesting periods? Briefly explain.