Backed by the U. S. government, these financial instruments are short-term debt obligations with a maturity of less than one year. They are considered risk-free investments. Issued by money-centered financial firms, these short- or medium-term insured debt instruments pay higher interest than a regular savings account. They are low-risk instruments and have low returns. Certificates of deposit These financial instruments are investment pools that buy such short-term debt instruments as Treasury bills (T-bills), certificates of deposit (CDs), and commercial paper. They can be easily liquidated. Money market mutual funds Issued by corporations, these financial instruments fund their long-term financing requirements and have less risk than equity securities.