Twitter on Friday unveiled its counterattack against Elon Musk by putting in place a corporate maneuver known as a poison pill.The strategy aims to slow or block Mr. Musk’s $43 billion bid to buy Twitter.A poison pill, devised by law firms in the 1980s to protect companies from corporate raiders, essentially lets a takeover target flood the market with new shares or allow existing shareholders other than the bidder to buy them at a discount. That means anyone trying to acquire the company must negotiate directly with the board.The pill will be triggered once any individual or a group of people working together buy 15 percent or more of Twitter’s shares. Mr. Musk currently owns more than 9 percent.Twitter said the plan will be …
