undervaluing

(verb) assign too low a value to. Synonyms: undervalue, underestimate. Example: "Don't underestimate the value of this heirloom-you may sell it at a good price."

(verb) esteem lightly. Synonyms: undervalue.

(verb) lose in value. Synonyms: depreciate, undervalue, devaluate, devalue. Example: "The dollar depreciated again."