Ask anyone in the markets today to name the biggest immediate risk to financial stability and the answer will be the explosion of the private credit industry, now estimated to be worthas much as $3 trillion. This is Wall Street doing what it has always been very good at: repackaging risky loans. Sure, it is profitable, in the way that lending money at high rates to people who badly need it usually is. But it is also precarious: It operates in the margins, with little transparency and even less oversight.