(corporation) the practice of purchasing enough shares in a firm to threaten a takeover and thereby forcing the owners to buy those shares back at a premium in order to stay in business WordNet 3.0 & Open English WordNet

Greenmail or greenmailing is the action of purchasing enough shares in a firm to challenge a firm's leadership with the threat of a hostile takeover to force the target company to buy the purchased shares back at a premium in order to prevent the potential takeover. Wikipedia

term in finance Wikidata

Profiting from an attempted hostile takeover by forcing the target company to buy back the hostile bidder's shares at an inflated price. Wiktionary