The story most often told relates to how each animal is said to attack. A bull will thrust its horns into the air, while a bear will swipe down. These actions metaphorically reflect the movement of a market, with bull markets trending up and bear markets trending down.
The correct answer is Stock market. The terms bull and bear is related to the Stock market. They are a speculator who buys for the settlement with a view of selling at some future date at a higher price and gaining the difference.