Since the gravity of the loss was out of proportion to the gravity of the breach, the motion court properly allowed equity to intervene under the circumstances presented ( see J.N.A. Realty Corp. v. Cross Bay Chelsea, 42 NY2d 392; Restoration Realty Corp. v. Robero, 87 AD2d 301, affd 58 NY2d 1089). Plaintiff paid rent for each of the four months in question, inadvertently failing to pay only the nominal cost-of-living increase, and invested substantial funds to improve the premises in reliance on its right to exercise the option. Moreover, the premises have been one of plaintiff's top producing retail locations, and defendant failed to establish that any prejudice resulted from the breach.