Funds from Schwab (its U.S. Small Cap ETF , SCHA ) and BlackRock (its iShares Russell 2000 , IWM ) are so efficient that their costs are negative.How does a fund wind up with a negative cost number?
Analyze the relationship between 'iShares' and 'BlackRock' within the context of the input sentence.
Options: operator, subsidiary, creator, legal form