The sharp bond market selloff is starting to pinch American consumers and companies, causing a mild economic tightening that, if sustained, could raise alarms at the Federal Reserve and even delay a plan to hike interest rates in coming months. U.S. mortgage rates have reached their highest level in a year-and-a-half, auto loans are getting a bit more expensive, and corporations across the board have seen their borrowing costs jump as U.S. and European debt retrenched in recent weeks. With benchmark U.S.