Combined assets in the nation's mutual funds decreased by $234.5 billion, or 2.1% to $10.886 trillion in January, according to a survey by the Investment Company Institute.

Led by international equity funds, stock funds showed the biggest turnaround, with inflows of $16.34 billion in January, compared to outflows of $3.53 billion in December. Investors have been fleeing U.S. stock funds for the past four months.

Most of the outflows came from a precipitous drop in money market mutual funds, which posted outflows of $102.72 billion for the month, compared to outflows of $852 million in December. Institutional money funds had outflows of $83.82 billion, while retail money funds lost $18.89 billion.

The Securities and Exchange Commission recently tightened its rules for money market funds, further lowering yields and raising transparency requirements.

Long-term stock, bond and hybrid funds had combined net inflows of $46.81 billion in January, verses inflows of $24.87 billion the previous month.

Most popular were bond funds, which had inflows of $26.94 billion in January, compared to $26.01 billion in inflows in December. Taxable bond funds had inflows of $22.46 billion, while municipal bond funds had inflows of $4.49 billion.