<P> where x i − 1 (\ displaystyle x_ (i - 1)) and x i (\ displaystyle x_ (i)) are the start and end discount factors associated with the relevant forward curve of a particular - IBOR index in a given currency . </P> <P> To price the mid-market rate of an IRS the above formula is re-arranged to: </P> <Dl> <Dd> R = ∑ j = 1 n 2 r j d j v j ∑ i = 1 n 1 d i v i (\ displaystyle R = (\ frac (\ sum _ (j = 1) ^ (n_ (2)) r_ (j) d_ (j) v_ (j)) (\ sum _ (i = 1) ^ (n_ (1)) d_ (i) v_ (i)))) </Dd> </Dl> <Dd> R = ∑ j = 1 n 2 r j d j v j ∑ i = 1 n 1 d i v i (\ displaystyle R = (\ frac (\ sum _ (j = 1) ^ (n_ (2)) r_ (j) d_ (j) v_ (j)) (\ sum _ (i = 1) ^ (n_ (1)) d_ (i) v_ (i)))) </Dd>

The market rate of interest is the same as the contract rate of interest