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A provision in some underwriting contracts allowing the underwriter to sell more shares to investors than were originally agreed. In an underwriting agreement, the underwriter agrees with the issuer of a security to place a certain amount with investors. If demand for the security exceeds the underwriter's supply, the greenshoe option allows the underwriter to avoid a sudden jump in price by increasing supply. Normally, the greenshoe option allows the underwriter to increase supply up to 15%. It is important to note that not all underwriting contracts have greenshoe options, especially in situations in which the issue is for a limited project for which the issuer only needs a certain amount of capital. It is also called an overallotment option.
An underwriting agreement provision that permits syndicate members to purchase additional shares at the original offering price. Shares in the greenshoe may consist of additional shares from the issuing company or may come from existing shareholders as a secondary offering. For example, the 2002 IPO of CIT Group included 200 million shares plus a greenshoe of 20 million additional shares that could be purchased by syndicate members at the $23 offering price within 30 days. Also called overallotment option.