Paying off an underwater mortgage and buying a better home could be the best tactic in this troubled market.

“If you are trading up, what better time than when interest rates are at record lows and the cost of the trade-up is much less than it used to be?” says Christopher J. Mayer, a Columbia Business School economist.

With 15-year fixed-rate mortgages at about 4.5 percent, it also makes sense to pay off the mortgage and keep the house. “At this point,” says Jay Brinkmann, chief economist of the Mortgage Bankers Association in Washington, D.C., “if they don’t have anything else that is bringing a tremendous return, then they are buying themselves an annuity by paying their house off sooner than they needed to.”

Source: The Wall Street Journal, M.P. McQueen