Definition of "buy up"

buy up

verb
third-person singular simple present buys up, present participle buying up, simple past and past participle bought up
1. (idiomatic, transitive) To buy the whole of; to purchase the entire stock of something.
2. (idiomatic, transitive) To buy whatever is available of something.
  Quotations
  According to this saga of intellectual-property misanthropy, these creatures [patent trolls] roam the business world, buying up patents and then using them to demand extravagant payouts from companies they accuse of infringing them. Often, their victims pay up rather than face the costs of a legal battle.
  2013 June 8, “Obama goes troll-hunting”, in The Economist, volume 407, number 8839, page 55
3. (idiomatic, transitive) To buy off; to pay in blackmail money or similar.
  Quotations
  Sir Leicester Dedlock, Baronet, it's for you to consider whether or not to buy this up. I should recommend, on the whole, it's being bought up myself; and I think it may be bought pretty cheap.
  1852 March – 1853 September, Charles Dickens, Bleak House, London: Bradbury and Evans, […], published 1853