Utilize the input text as a context reference, choose the right relationship between 'iShares' and 'BlackRock' from the options.
Options: owner of, product/material produced, operator, location of formation

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