Non-U.S. stock funds also posted an outflow for the week, losing an estimated $548 million, more than double the previous week's $225 million outflow.
Bond funds, on the other hand, attracted $8.11 billion in estimated inflows, up 54% from the $5.28 billion they took in the week before. Of the $8.11 billion, $6.80 billion went to taxable bond funds with the remaining $1.31 billion going to municipal bond funds.
Hybrid funds - those that invest in both stocks and fixed income securities - were also winners, taking in an estimated $1.31 billion, up 43% from $910 million a week earlier.
All told, mutual funds posted $6.12 billion in estimated inflows for the week, almost twice the previous week's $3.10 billion inflow.
The weekly fund flow estimates are derived from data covering more than 95% of industry assets, according to ICI. The statistics cover long-term mutual funds, those the ICI defines as investing in long-term instruments.