Despite the Fed's rate-cut cycle opening, investors are still pouring a large amount of funds into US money market funds, driving the assets under management to a record high.

Data released by the Investment Company Institute on Thursday shows that in the week ending September 25, approximately $121 billion flowed into US money market funds. Total assets reached a record $6.42 trillion.

At a time of such strong demand, some fund managers - including Jerome Schneider, the short-term investment portfolio manager and funding manager at Pacific Investment Management - believe it is time to withdraw from money market funds. With US policymakers already starting to lower benchmark interest rates from a 20-year high, the debate over whether these funds will remain popular is heating up.

However, even though Fed officials cut rates by 50 basis points in September, money market funds often take longer to be affected compared to banks.