8.55%. If the credit rating of the Debentures is downgraded to AA-, the coupon rate will be increased by 0.50%. For any subsequent downgrade from AA-, the coupon rate will be increased by 0.25% for each additional notch until A rating. In case of further downgrade below A, the coupon rate will be increased by 0.50% for every notch thereafter. There will be no step-up for downgrade from AA+ to AA. If the rating is upgraded after a downgrade, the coupon rate will be decreased by 0.50% for each notch of upgrade until A rating and by 0.25% for each notch thereafter.