How to calculate annualized Swap Rate (from quarterly data)

You’ll be most likely given four interest rates or discount factors.

Maturity	Annualized Rate	Discount Factor
90	R1	1 /(1 + (R1 * (90/360))) = Z1
180	R2	1 /(1 + (R2 * (180/360))) = Z2
270	R3	1 /(1 + (R3 * (270/360))) = Z3
360	R4	1 /(1 + (R4 * (360/360))) = Z4

C = (1 – Z4) / (Z1 + Z2 + Z3 + Z4)

Assuming quarterly date Annualized Swap Rate = 4C or C/(90/360)