CDs offer a fixed rate of return. The value of a CD is guaranteed up to $250,000 per depositor, per insured institution, per insured institution, by the Federal Deposit Insurance Corp. (FDIC). An investment in a money market fund is not insured or guaranteed by the FDIC or any other government agency. A money market fund seeks to maintain the value of $1.00 per share although you could lose money. The FDIC is an independent agency of the US government that protect the funds depositors place in banks and savings associations. FDIC insurance is backed by the full faith and credit of the United States government.