This paper investigates whether mutual fund families acting as service providers in 401(k) plans display favoritism toward their own affiliated funds. Using a hand‐collected data set on the menu of investment options offered to plan participants, we show that fund deletions and additions are less sensitive to prior performance for affiliated than unaffiliated funds. We find no evidence that plan participants undo this affiliation bias through their investment choices. Finally, we find that the subsequent performance of poorly performing affiliated funds indicates that this favoritism is not information driven.