The combined assets of the nation’s mutual funds decreased by $398.0 billion, or 3.3 percent, to $11.621 trillion in August, according to the Investment Company Institute.

Also falling: the nation’s exchange-traded funds, which have been rising in popularity and have been used extensively by institutional investors, when trading in the nation’s stock markets turn volatile.

Assets of all exchange-traded funds fell in August by $44.99 billion, or 4.1 percent, to $1.041 trillion, the ICI reported.

This came after ETF assets increased $239.86 billion, or 29.9 percent, during the prior 12 months.

Hard hit again were funds that invest long-term in U.S. stocks. Such mutual funds posted an outflow of $25.62 billion in August, after an outflow of $28.05 billion in July.

World equity funds (U.S. funds that invest primarily overseas) posted an outflow of $3.68 billion in August, vs. an outflow of $3.01 billion in July.

Hybrid stock-bond funds posted an outflow of $3.43 billion in August, compared with an outflow of $51 million in July.

Bond funds had an outflow of $4.06 billion in August, compared with an inflow of $9.85 billion in July.

Money market funds had an inflow of $71.76 billion in August, compared with an outflow of $118.90 billion in July.

Domestic mutual funds that invest in U.S. stocks remain hard hit. In September, in its weekly tallies, investors pulled $3.89 billion out of such funds in the week ended Sept. 21, $2.65 billion the prior week and $1.1 billion in the first week of the month.

-- This article first appeared on Securities Technology Monitor.