"The [SEC] voted to adopt changes to modernize and enhance the reporting and disclosure of information by registered investment companies and to enhance liquidity risk management by open-end funds, including mutual funds and exchange-traded funds (ETFs).... [Vanguard's John Hollyer] explained that this means when cash flows in or out rise above a certain threshold, the mutual fund could choose to adjust the cost of the fund that day to account for the number of investors who bought or sold on that day. Long-term investors, such as retirement plan participants, would benefit from this because they would not bear the cost of frequent traders."