What Is the Difference Between Amortized Cost & Market Value of Securities?

Amortization is a process, and market value marks a place in time on securities -- stocks, bonds and other investments -- on which you expect a return. Tracking amortization requires some patience and information; achieving a positive market value requires picking the right timing and conditions in which to liquidate the security.

Expenses, such as brokerage fees -- or, in the case of bonds and similar instruments, earnings -- affect the value of a security over its lifetime. For example, a bond bought at $18 and 2 percent earns $0.72 annually. If the interest is amortized, the bond earns $.06 per month, so its amortized cost -- cost minus earnings -- of the bond drops by $.06 per month. Fees associated with acquiring or divesting the security should also be broken down into monthly increments and added to the amortized cost progression. Understanding and using an amortized cost chart helps you decide whether you're making or losing money on a security over the long run.

What a security sells for on a given day determines its market value. By comparing this figure with your amortized cost you can tell whether you're making money or losing on your investment. Unlike amortized cost, which typically progresses downward at a consistent rate, market value can fluctuate rapidly. Market value is relative value based on the universe of intangibles that control the market. Even bond market values can vary, depending on their interest rate at issue.