If you say that something goes, comes, or is under the hammer, you mean that it is going to be sold at an auction.

What does it mean to be under the hammer?

come​/​go under the hammer ​Definitions and Synonyms

phrase. DEFINITIONS1. to be sold at an auction (=a public sale in which objects are sold to the person who offers the most money) Synonyms and related words.

What does put down the hammer mean?

(idiomatic) To drive quickly; to step on the accelerator.