Aug. 12 (Bloomberg) — John Turner suspected that brokers were encouraging federal workers to ditch their top-flight retirement plan. So he went under cover.

The former U.S. Labor Department economist called representatives at companies such as Bank of America Corp., Charles Schwab Corp. and Wells Fargo & Co. He identified himself as a potential client grappling with what to do with his own nest egg.

Turner thought he knew the right answer: Leave it alone. As a legacy of his government service, he kept his money in the Thrift Savings Plan, considered the gold standard of 401(k)-type programs for its rock-bottom fees. Yet all but one company told him to roll over all his money into individual retirement accounts. On average, stock funds charge almost 50 times more than the government plan.