According to the fund tracker, around four in ten money market funds had returns of zero for Thursday, as investors digested the implications of Lehman Brothers' bankruptcy and Merrill Lynch's $50 billion merger with Bank of America.
Confidence was further knocked by the Reserve Primary Fund - a flagship money fund - announcing that its asset value stood at below $1 a share.
Known as "breaking the buck", this is a near-unique position for such low-risk funds to be in - and last occurred 14 years ago.
However, Lipper's reading was taken prior to the announcement of the US government's $700 billion "bad bank" rescue fund, which sent markets soaring the following day.
Included in the package of reforms, since submitted to congress, was $400 billion of insurance for money market funds.
Speaking to CNBC about the new figures Jeff Tjornehoj, senior research analyst at Lipper, commented: "This is unprecedented in recent history."
Money market funds retain around $3.4 trillion in assets.