From Longman Dictionary of Contemporary Englishbuy something ↔ up phrasal verbBUYto quickly buy as much of something as possible, for example land, tickets, or goods Much of the land was bought up by property developers. → buy→ See Verb table
Examples from the Corpus
buy up• Its art renaissance began in 1996, when the new owners bought it up.• Make a few phone calls and see what pity could buy.• Our advice is: Always, always register every product you buy!• But much of what they buy ends up being returned or hidden away at the back of a drawer.• The buy was set up by the Naval Criminal Investigative Service, whose agents were investigating possible drug use at the academy.• He had even bought a house up the road from Sunset.From Longman Business Dictionarybuy something → up phrasal verb [transitive]COMMERCE to quickly buy as much as possible of something such as land or ticketsMuch of the land has been bought up by property developers. → buy→ See Verb table 