At least $500 billion in assets around the world are managed in accordance with Sharia, or Islamic law, and the sector is growing at more than 10% per year. In spirit, Islamic finance seeks to promote social justice by banning exploitative practices. In reality, this boils down to a set of prohibitions — on paying interest, on gambling with derivatives and options, and on investing in firms that make pornography or pork. No one can say for sure how many of the world’s 1.3 billion Muslims will demand Sharia-compliant financial products, but if even a fraction do, the world’s largest banks will be happy to oblige.