I am trying to learn about valuation and yields for treasury bonds. For the Treasury Bond maturing on 11/15/2018, initially sold in 1988 with a 9% coupon, it states that the yield to maturity is 1.66%. Now a secondary sale with an ask price of 101.856%. Last coupon was paid 5/15/2018.
Shouldn't the yield if you bought it now be ($45-$18.56)/$1018.56 = 0.0260 as there will be the final coupon payment and face value paid at maturity? Is the quoted yield to maturity based on buying it when initially sold in 1988 and the current price?