a speculator in the stock exchange market who sells securities in expectation of a fall in their prices is called?

A speculator in the stock exchange market who sells securities in expectation of a fall in their prices is called a "bear". The term "bear" is used to describe someone who believes that the market or a particular stock is going to go down or decline in value. A bear may sell securities or stocks that they do not currently own, hoping to buy them back at a lower price in the future, thereby making a profit from the difference. The opposite of a bear is a "bull", which is a term used to describe someone who believes that the market or a particular stock is going to go up or increase in value. Both bears and bulls can be speculators or investors, but they have different views on the future direction of the market. In summary, a "bear" is a speculator in the stock exchange market who sells securities in anticipation of a price decline.