Hartford Financial Services Group Inc. and Prudential Financial Inc. say their money market mutual funds will take part in the new guaranty program recently established by the U.S. Treasury.

The Treasury program will insure the holdings of any publicly offered money market mutual fund – either retail or institutional – that pays a fee to join the program.

Officials expect the program to last for 3 months and say they could continue it for up to a year.

The program will protect shareholders of eligible money market funds from a decline in value of up to the amounts held in their accounts as of the close of business Sept. 19, officials say.

The moves by Hartford, Hartford, and Prudential Financial, Newark, N.J., to join the program follow announcements from Fidelity Investments, Boston, and Vanguard Group, Valley Forge, Pa., that they are joining the program.

Hartford says it will put the Hartford Money Market and Hartford Money Market HLS funds in the guarantee program.

Hartford is emphasizing that its money market funds do not hold any debt from Lehman Brothers Holdings Inc., New York, in their portfolios.

Prudential says its JennisonDryden and Target mutual funds, along with its Prudential Institutional Liquidity Portfolio, will take part in the Treasury program.