Green Shoe Option

A provision contained in an underwriting agreement that gives the underwriter the right to sell investors more shares than originally planned by the issuer. This would normally be done if the demand for a security issue proves higher than expected. It is legally referred to as an over-allotment option. A greenshoe option can provide additional price stability to a security issue because the underwriter has the ability to increase supply and smooth out price fluctuations if demand surges.