關於 T Bill

        今天10/5/2023, 周四, 是 T Bill 中 4 week 和 8 week 的 auction day，也是13 week，26 week， 和 52 week的 issue day。

        下麵把6期（4、8、13、17、26、52 week）的 T Bill 匯總如下，包括它們的最新 auction出來的利率，以及計算後的等效利率，以作對比。

為了更為清晰，做出當今的 T Bill 周數和等效利率的關係曲線, 並和一年前的數據相對比：

T Bill 利率計算如下：

Treasury Calculation Examples 033104 v11.xls (treasurydirect.gov)

隻是讀起來很頭疼。最後抄來一段CD 利率的計算方法：

Formula for Calculating CD Interest

A = P(1+r/n)(nt)

• A is the total that your CD will be worth at the end of the term, including the amount you put in.
• P is the principal, or the amount you deposited when you bought the CD.
• R is the rate, or annual interest rate, expressed as a decimal. If the interest rate is 1.25% APY, r is 0.0125.
• n is the number of times that interest in compounded every year. Most CDs pay interest that is compounded daily, so n = 365. Check with your bank to verify the interest is compounded daily.
• t is time, or the number of years until the maturity date.