The shakeout in the $20 trillion US commercial real estate market has long been delayed for a simple reason: No one could figure out just how much properties were worth. And, more crucially, few wanted to.Since the Covid-19 pandemic upended the use of real estate around the world, lenders have had little incentive to get tough on borrowers squeezed by soaring interest rates and take on loans that had lost value. Transactions ground to a halt as potential sellers were unwilling to unload building...