Short selling requires borrowing a security from a broker in order to selling it, then buying back the security to return it to the broker. (sparxtrading.com)
As with any security, going short means borrowing the security and anticipating a fall in price, after which the investor can buy it and return what has been borrowed. (investopedia.com)
In the 1920's and 1930's it refers to the group of members firms that lend or borrow securities needed to cover the positions o customers who have sold short securities. (teenanalyst.com)