GOING LOWER: BlackRock Inc.'s iShares unit is reducing the investment fees charged at six of its largest exchange-traded funds. Its two lowest-cost stock ETFs will charge expense ratios of 0.07 percent, or 70 cents a year for every $1,000 invested. Expenses at other ETFs will range from 0.08 percent to 0.18 percent.

COMPETITIVE MOVES: Vanguard and Charles Schwab have also recently cut ETF fees, in some cases below levels charged by iShares, the largest ETF provider.

FUND RIVALRY: The lowest-cost ETFs are undercutting expenses charged by many index mutual funds. Both seek to match rather than beat the market.