A bull is a stock market speculator who buys a holding in a stock in the expectation that in the very short-term it will rise in value whereupon they will sell the stock to make a quick profit on the transaction. Strictly speaking the term applies to speculators who borrow money to fund such a purchase, and are thus under great pressure to complete the transaction before the loan is repayable or the seller of the stock demands payment on settlement day for delivery of the bargain. If the value of the stock falls contrary to their expectation, a bull suffers a loss, frequently very large if they are trading on margin . A bull has a great incentive to "talk-up" the value of their stock or to manipulate the market in their stock, for example by spreading false rumour, to procure a buyer or to cause a temporary price increase which will provide them with the selling opportunity and profit they require. A bull must therefore be contrasted with an investor , who purchases a stock in expectation of a medium-term (say 5 years) or long-term increase in value due to the underlying performance of the company and its assets . The speculator who takes a directly opposite view to the bull is the bear , who speculates on a stock decreasing in value, having sold short . A bull market is a period during which stock market prices rise over a sustained period, therefore to the advantage of bulls.