Critic Feisal Khan argues that in many ways Islamic finance has not lived up to its defining characteristics. Risk-sharing is lacking because profit and loss sharing modes are so infrequently used. Underlying material transactions are also missing in such transactions as ""tawarruq", commodity "murabahas", Malaysian Islamic private debt securities, and Islamic short-sales". Exploitation is involved when high fees are charged for "doing nothing more substantial than mimicking conventional banking /finance products". Haram activities are not avoided when banks (following the customary practice) simply take the word of clients/financees/borrowers that they will not use funds for un-Islamic activities.