Pension and health-care related costs are growing so fast that POBs are one of several difficult options to cover these costs,” said Jon Schotz, managing partner at Saybrook Fund Advisors. “But I don’t know why issuers would do POBs, if you look over time, they haven’t worked. It’s very rare that municipalities can invest pension assets and see a return at a rate higher than their borrowing costs without taking on more risk.