Sustainable Shadow Banking

Banking regulation is beneficial because it constrains banks' portfolios to prevent excessive risk taking. But given that regulators usually know less than a bank about its investment opportunities, regulation comes at the cost of foregoing profitable investments. I argue that shadow banking improves welfare because it provides a channel to escape excessive regulation that is asymmetrically more valuable for banks with access to efficient investment opportunities. I propose a novel intervention that improves welfare further by taxing shadow activities, subsidizing regulated activities and allowing banks to self-select into being regulated or not.