If someone refinances a 30 year 6 percent mortgage (with 27 years of payments left on it) into a 15 year 2.86 percent mortgage, the payment goes up by 10 percent, which is not nothing. But within 5 years, more than 25 percent of the principal on the 15 year mortgage is paid down. For those who can afford the payment, this would largely solve the underwater mortgage problem.
