What is Twitter’s ‘poison pill’ supposed to do against Elon Musk's takeover bid?

Elon Musk, Tesla CEO, attends the opening of the Tesla factory Berlin Brandenburg in Gruenheide, Germany, March 22, 2022. Picture: Patrick Pleul/Pool Photo via AP, File

Twitter is trying to thwart billionaire Elon Musk’s takeover attempt with a “poison pill” — a financial device that companies have been wielding against unwelcome suitors for decades.

– What are poison pills supposed to do?