Greenmail or greenmailing is the practice of purchasing enough shares in a firm to challenge a firm's management or leadership and even threaten a corporate takeover, thereby forcing the target firm to buy those shares back at a premium in order to suspend the potential takeover or to take other actions that remove equity from the greenmailer and return it to the target firm.
The term is a neologism derived from blackmail and greenback as commentators and journalists saw the practice of said corporate raiders as attempts by well-financed individuals or their operating companies to blackmail a company into handing over money by using the threat of a takeover.
Corporate raids occasionally aim to generate large amounts of money by hostile takeovers of large, often undervalued or inefficient (i.e. non-profit-maximizing) companies, by either asset stripping and/or replacing management and employees. In other circumstances, the greenmailer seeks out assets the target company has built up as equity, such as real estate, and attempts to have the target company dispose of those assets and lease them back via a recurring lease payment, while returning the sold-off real estate to shareholders as a special dividend.
One example of this practice was the attempted takeover by William Ackman's Pershing Square Capital Management of American retailer Target, which had a large inventory of mature or nearly mature real estate properties in its corporate portfolio. Ackman attempted to have these assets spun off as an IPO, along with a partial sale of Target's credit card unit and the execution of share buybacks, which reduce the number of shares outstanding by using corporate equity and earnings to repurchase existing shareholders' positions.
Once having secured a large share of a target company, instead of completing the hostile takeover, the greenmailer offers to end the threat to the victim company by selling his share back to it, but at a substantial premium to the fair market stock price.
From the viewpoint of the target, the ransom payment may be referred to as a goodbye kiss. The origin of the term as a business metaphor is unclear. A company which agrees to buy back the bidder's stockholding in the target avoids being taken over. In return, the bidder agrees to abandon the takeover attempt and may sign a confidential agreement with the greenmailee, guaranteeing not to resume the maneuver for a period of time.