New disclosure rules and the threat of fiduciary violation lawsuits have helped bring down investment management, recordkeeping and other fees in 401(k) and other retirement accounts. Now revenue-sharing is following suit.

According to a 2013 survey by Boston-based investment consultancy NEPC, total plan costs for sponsors declined 0.02 percent from 2012 to 2013, falling to 0.53 percent. That's equivalent to a yearly charge of $5.30 for every $1,000 invested. That figure had been 0.59 percent in 2010, so the savings are in the many millions of dollars.

NEPC's survey also found that revenue-sharing arrangements – used to help offset, or in some cases, to pay for all plan-related expenses – began to decline in 2010 and continued to do so in 2013. It found that 13 percent of plans had no form of revenue sharing whatsoever, a figure that most expect will only grow.