In the Unite States and some other countries, corporations can buy back their own stock in a share repurchase, also known as a stock repurchase. There has been a meteoric rise in the use of share repurchases in the U.S. in the past twenty years, from $5b in 1980 to $349b in 2005. A share repurchase distributes cash to existing shareholders in exchange for a fraction of the firm's outstanding equity. That is, cash is exchanged for a reduction in the number of shares outstanding. The firm either retires the shares or keeps them as treasury stock, available for re-issuance. Under U.S. corporate law there are five primary methods of stock repurchase: open market, private negotiations, repurchase put rights, and two variants of self-tender repurchase, a fixed price tender offer and a Dutch auction.