Cash funds saw a "huge" inflow of $112.7 billion in the latest week, BofA said, citing EPFR data.

The data includes flows in the days after the collapse of Silicon Valley Bank last Friday. Since then, markets have been roiled, but fears have somewhat receded after a series of lifelines for struggling banks helped restore some investor confidence.

Inflows into cash for the first quarter of 2023 are on course to be the highest since the second quarter of 2020, BofA said.

Meanwhile, equity funds saw a "tiny" weekly outflow of $26 million, and investors pulled $2.3 billion from bonds and put $600 million into gold.

Since the flow data's cut-off on Wednesday, the Swiss National Bank has stepped in to offer Credit Suisse a $54-billion loan to shore up liquidity and restore investor confidence while the U.S.'s First Republic Bank received a $30 billion lifeline from a cohort of large U.S. banks.

The turmoil in markets has spooked investors, but BofA said equity flows had been unchanged week-on-week and there was "no equity capitulation."

Even so, in Friday's report, BofA highlighted that emergency borrowing by banks could lead to tighter lending standards, a small business credit crunch and higher unemployment.

There was a "flight to quality" in fixed income according to BofA, with $9.8 billion poured into Treasuries - the largest weekly inflow since May 2022. Emerging market debt recorded its biggest outflow since November, of $3.1 billion.

BofA's bull and bear indicator - a measure of market sentiment - dropped sharply to 3.5 from 4.2 the previous week, its lowest since January, with BofA citing "weaker credit flows and worsening breadth in stocks."