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Annual percentage yield (APY) is a normalized representation of an interest rate, based on a compounding period of one year. APY figures allow for a reasonable, single-point comparison of different offerings with varying compounding schedules. However, it does not account for the possibility of account fees affecting the net gain. APY generally refers to the rate paid to a depositor by a financial institution, while the analogous annual percentage rate (APR) refers to the rate paid to a financial institution by a borrower. To promote financial products that do not involve debt, banks and other firms will often quote the APY (as opposed to the APR because the APY represents the customer receiving a higher return at the end of the term). For example, a CD that has a 4.65 percent APR, compounded monthly, for 8-months would instead be quoted as a 4.75 percent APY.〔http://pubs.cas.psu.edu/FreePubs/pdfs/ui392.pdf〕 ==Equation== One common mathematical definition of APY uses this effective interest rate formula, but the precise usage may depend on local laws. : where : is the nominal interest rate and : is the number of compounding periods per year. For large ''N'' we have, approximately, : where ''e'' is the base of natural logarithms (the formula follows the definition of ''e'' as a limit). This is a reasonable approximation if the compounding is daily. Also, it is worth noting that a nominal interest rate and its corresponding APY are very nearly equal when they are small. For example (fixing some large ''N''), a nominal interest rate of 100% would have an APY of approximately 171%, whereas 5% corresponds to 5.12%, and 1% corresponds to 1.005%. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「annual percentage yield」の詳細全文を読む スポンサード リンク
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