The prevailing view of shadow banking is that it is all about regulatory arbitrage – evading capital requirements and exploiting ‘too big to fail’. This column focuses instead on the tradeoff between economic growth and financial stability. Shadow banking transforms risky, illiquid assets into securities that are – in good times, at least – treated like money. This alleviates the shortage of safe assets, thereby stimulating growth. However, this process builds up fragility, and can exacerbate the depth of the bust when the liquidity of shadow banking securities evaporates.