For the 33rd consecutive month through December, investors withdrew money from active managers. Last year, passively funds attracted almost $505 billion.
Not only are traders worried about tightening monetary policies from the Fed, but also the Trump administrations struggle to enact pro-growth policies.
The iShares unit has had other departures in recent years.
So far this year, 1.2 million shares were traded daily on average on the Nasdaq Biotechnology ETF, down from 2.2 million in the same period in 2014.
A single percentage point increase in ETF ownership has demonstrable effects on an individual stock, researchers said.