買(か)い占(し)め

かいしめ
noun
buying up; hoarding; cornering the supply
shoppingeconomics
1. buying up; panic hoarding; cornering the supply
Buying all or most of an available stock, either by consumers stripping the shelves in a shortage or by a buyer cornering a market for profit. The noun form of 買(か)い占(し)める.
マスクの買(か)い占(し)めが起(お)きた。
Panic buying of masks broke out.
There was a notice asking customers to refrain from bulk-buying.
Reports of short supply triggered hoarding, which only made the shortage worse.

Common collocations

Usage

The word carries clear disapproval: the buyer is taking more than their share or manipulating supply. Ordinary bulk shopping is まとめ買(が)い, which is neutral and even thrifty.