Short answer: Whatever you do, don't leave it in your old employer's plan. You want to roll it over to an individual retirement account, also known as an IRA.
A few years back, my husband and I were on our way to the airport. We were flying to Phoenix for my grandmother's 85th-birthday celebration. We had the radio on in the car, listening to an investment show on the radio (not mine, obviously).
A caller asked the host whether or not he should rollover his 401(k) into an IRA when he left his old employer. The host emphatically replied yes, the caller should not leave his 401(k) with his former employer.
Then the caller said, “I've always heard that. Can you tell me why that is?” The host then explained that you are in danger of losing your 401(k) if your former employer goes out of business. The radio show host gave the right answer, but then he gave the wrong reason!
Your employer, current or former, is not the custodian of your 401(k) account. The employer doesn't hold the money. A third party does. So the concern isn't that your employer may go bankrupt.
So you may be thinking to yourself, what if the bank, brokerage or insurance company who has custody of my 401(k) money goes under - like Bear Stearns did?
Not to worry. The money you have invested in your employer sponsored retirement plan, or any brokerage account for that matter, is held in completely separate subaccounts. It cannot be comingled with other funds and the custodian can't use your money to pay its bills or debt under any circumstances.
In the off chance your plan custodian did go under, your company, which is called the plan sponsor, will either transfer the plan to another custodian, or, more likely, the custodian will be taken over and your company will become a client of that new company.
So if bankruptcy isn't the issue, why is it so important to roll your 401(k) or 403(b) to an IRA when you leave your employer? The primary driver of the move is that you have more investment alternatives in an IRA than in an employer sponsored plan.
In a 401(k), you are probably limited to the mutual funds offered by your plan administrator. In an IRA, you can buy and sell the entire universe of investment alternatives - including all stocks, bonds, mutual funds, options, real estate, and even privately held companies.
While that is the most important reason to roll your 401(k) over into an IRA when you leave, there are others.
If invested properly, your fees will probably be lower in an IRA than a 401(k). Fees are very important for three reasons: 1) reducing fees is risk free return - it may be the only free lunch in investing; 2) reducing fees leaves more money in your pocket to compound over time and compounding is a miraculous thing; and 3) studies show the one thing most correlated with performance, over time, is not the fund manager, the sector, the asset class or the historical performance, but low fees.
As a general rule, fees are highly inversely correlated to portfolio performance - the higher the fees, the worse the performance. The lower the fees, the better the performance - which is, of course, a very practical reason why you should learn to be your own money manager.
Another reason is easier access to your money, although I'm not sure this is such a good thing. If you want to rob your retirement account, you don't have to ask for permission, nor is there any bureaucratic paperwork. You have a thousand miles of rope to hang yourself with.
Another benefit is you can split IRAs between multiple beneficiaries and IRAs are easier to allocate when you have non-spousal heirs.
While you are employed, you have to try to max out your employer sponsored retirement plan if you can. At a minimum, you have to contribute enough to get the employer match, if there is one. But if there is a silver lining to losing your job, being able to self-direct your retirement funds is one.
Get that money rolled over to an IRA as soon as you can. Never leave your 401(k) with your old employer, and even worse, never ever roll your old 401(k) money into your new employers plan when you are lucky enough to find a new job.