I set up my small company's 401k through Vanguard. I believe large companies get to deal with Vanguard directly, but small companies work through a company called Acensus. They offer most (if not all) of the Vanguard products and very low expense ratios.
It was a few years ago when the plan was set up, but I remember that Employee Fiduciary was less expensive than Vanguard when total assets in the plan were under a million, and then Vanguard/Acensus was less after that. In hindsight, we probably should have gone with Employee Fiduciary, but the "Vanguard" name made it easier to get people on board with that specific plan.
