In the context of the input sentence, determine the relationship between 'iShares' and 'BlackRock'.
Options: owner of, product/material produced, location of formation, operator

Trading in BlackRock Inc.’s iShares ETFs was paused more than 200 times, while those sponsored by State Street and Vanguard were halted more than 70 times, according to data from Nasdaq OMX Group Inc.
operator