greenmail
From Longman Business Dictionarygreenmailgreen‧mail /ˈgriːnmeɪl/ noun [uncountable]FINANCE when a company buys back its stock from a SUITOR (=a company that is trying to take it over), often for a very high price, to try to prevent a TAKEOVEROne of Japan’s wealthiest men, he has a history of speculation in stocks and real estate and is renowned for his attempts at greenmail.