The mortgage by deposit of title deeds — popularly called an "equitable mortgage" — is one of the most widely used instruments in Indian real-estate financing, yet it remains one of the most frequently misunderstood. Under Section 58(f) of the Transfer of Property Act, 1882 (TPA), a mortgage is created by deposit of title deeds in the notified towns of Calcutta, Madras, Bombay, and other towns as the State Government may notify, without any registered instrument. This exception to the general requirement of registration under the Registration Act, 1908 has generated substantial litigation, and the Supreme Court has over the decades clarified its contours significantly.