When a right to sell a security is acquired, it is known as __________.

When a right to sell a security is acquired, it is known as put option. In finance, a put or put option is a stock market device which gives the owner the right, but not the obligation, to sell an asset (the underlying), at a specified price (the strike), by a predetermined date (the expiry or maturity) to a given party (the seller of the put).