Refer to the input text as context and select the correct relationship between 'iShares' and 'BlackRock' from the available options.
Options: subsidiary, legal form, creator, operator

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?
operator