<prompt> Human: I am starting a new job. My old 401k was with Fidelity. My new one will be with Merrill Lynch. Does the old one just stop getting contributions and stay there or can I some how combine the old one with the new one? If so how do I go about combining them? Are there any penalties for that? Is there a time limit or period of time that you have to combine? Thanks.  <response>: Personally, I took my first one and rolled it into an IRA at Vanguard. I chose to invest it in their 500 Index Fund VFINX, but you can choose any fund you like. Vanguard made the whole process really easy for me. 