With expense ratios of 0.03% to 0.13%, these exchange-traded funds offer diverse market exposure with less fee-driven drag on your returns.Exchange-traded funds (ETFs) now hold $10.3 trillion in U.S. assets, yet most investors still overpay for the basic market exposure that such funds provide. While the average index equity ETF charges 0.14%, Vanguard continues to undercut the competition through its unique investor-owned structure -- the fund company is literally owned by its funds, which are owned by sha ...