If brokers had to put their clients’ interest ahead of their own, those clients would pay more for financial advice and their investments, according to a study commissioned by the Securities Industry and Financial Markets Association (SIFMA), a group representing megabrokers and banks that are trying to influence a forthcoming rulemaking from the Securities and Exchange Commission.

Knut Rostad, chairman of a financial advisors advocacy group, the Committee for the Fiduciary Standard, called the SIFMA report “a fantastic mythology.” “It’s so incoherent as to defy objective evaluation,” Barbara Roper of the Consumer Federation of America wrote to the SEC.