Did you know that if you work for a company and accumulate stock of that company in its 401K program, when you withdraw the stock out of your 401K in your golden years, you pay tax on the cost basis of the stock, NOT the cash value.  If you transfer it into your IRA, you lose this tax advantage, and pay taxes on the cash value of the stock, not the cost basis.  

So, for example, if you had accumulated company stock worth $100,000 in cash value at a cost basis of, say $10,000, you pay taxes on $10,000 when you take the money out of your 401K, but you would pay taxes on $100,000 if you transfer the stock from your 401K to your IRA and then take it out.  

So basically, if you accumulate stock of your employer in your 401K and then leave that employer for another employer, you are better off leaving the stock in your 401K rather than transferring the stock to your IRA to gain control of your investments -- unless, of course, you believe that stock will be a terrible investment.