Frequent flyers warned about sitting on mountain of unused miles

Frequent flyers, consider yourselves warned: Sitting on a pile of unused airline miles could cost you.

Liabilities tied to the five most valuable airline-loyalty programs in the US soared almost 12% to $27.5 billion last year, according to new analysis by LendingTree Inc’s consumer-finance website ValuePenguin. Airlines looking to shore up their balance sheets could reduce the value of those rewards or reinstate policies that allow miles or points to expire, the firm warned.

“Especially in a time where airlines have gone through such financial issues, it would be easy to see that they would look at some sort of devaluation of the miles and points as a way to make up a little bit of financial ground,” Matt Schulz, LendingTree’s chief credit analyst, said in an interview.