Taxpayer Identification Number, a U. When you invest in a municipal bond, you might help improve a local school system, build a hospital, or develop a public garden. These agencies use a combination of letters, numbers, and symbols to indicate the creditworthiness of bond issuers. There are two ways to make money by investing in bonds. A broker, for example, might sell a certain bond at a premium meaning, above its face value , while another broker might charge an even higher premium. Suddenly, your bond drops in value, and if you hold it, you’ll lose out on potential earnings by getting stuck with that lower rate. Your ability to sell a CD on the secondary market is subject to market conditions.