Number of shares traded in a company or an entire market during a given period. Unusually high volume days typically correspond with the announcement of company news, either positive or negative. In the absence of news, high volume can indicate institutional (or professional) buying and selling. Technical analysis places a great emphasis on the amount of volume that occurs in the trading of a security. A sharp rise in volume is believed to signify future sharp rises or falls in price because it reflects increased investor interest in a security or a market.