The total assets managed by the world's 500 biggest fund houses hit an all-time high of $81.2 trillion in 2016, research showed on Monday, a 5.8-percent increase on the previous year.
Although a comfortable majority of funds are still actively managed, the research from advisory firm Willis Towers Watson showed, the proportion of passively managed funds climbed to 21.6 percent. That was up from 20.3 percent the previous year, and from 16.5 percent five years ago.
"We expect that this trend will continue to put downward pressure on traditional fee structures, particularly amongst active managers seeking to remain competitive and to maximise value to investors," said Willis Towers Watson's global head of manager research, Luba Nikulina.
U.S. fund managers saw their assets increase 7.7 percent to $47.4 trillion, while European managers saw a 2.8-percent increase, to $25.8 trillion.
UK-based fund management firms saw their assets fall for a second straight year, however, by 4.5 percent to $6.3 trillion.
BlackRock remained the top fund manager, with $5.1 trillion under management, followed by fellow U.S. firm Vanguard, with just under $4 trillion.