<a href="https://www.thenationalnews.com/business/money/2022/04/14/what-is-elon-musks-net-worth/" target="_blank">Elon Musk</a> used an upside-down smile emoji on Saturday in a response to a tweet he sent more than four years ago about how much it would cost to buy Twitter. The Tesla chief executive, who earlier this week <a href="https://www.thenationalnews.com/business/markets/2022/04/14/elon-musk-offers-to-buy-100-of-twitter-for-roughly-43bn/" target="_blank">launched a $43 billion hostile takeover offer</a> for the social media company, was commenting on a tweet thread from December 2017 in which he expressed his admiration for Twitter and asked how much it cost to buy. The “upside-down smile” emoji is used as an indication of frustration or bemused resignation, according to emojipedia. Twitter on Friday adopted a so-called “<a href="https://www.thenationalnews.com/business/2022/04/15/twitter-moves-to-shield-itself-from-musk-takeover-bid/" target="_blank">poison pill” provision</a> in an attempt to thwart Mr Musk’s takeover attempt. The social media company's board adopted a limited-duration shareholder rights plan, which would enable its shareholders to buy additional stock, it said. Under the plan, "the rights will become exercisable if an entity, person or group acquires beneficial ownership of 15 per cent or more of Twitter's outstanding common stock in a transaction not approved by the board", Twitter said. On Thursday, Mr Musk, founder and chief executive of electric vehicle maker <a href="https://www.thenationalnews.com/business/2022/04/07/tesla-marks-opening-of-texas-gigafactory-with-flashy-celebration/">Tesla</a> and rocket company <a href="https://www.thenationalnews.com/world/us-news/2022/02/10/elon-musk-to-give-spacex-starship-update/">SpaceX</a>, offered to <a href="https://www.thenationalnews.com/business/markets/2022/04/14/elon-musk-offers-to-buy-100-of-twitter-for-roughly-43bn/">buy 100 per cent of Twitter </a>for roughly $43 billion, proposing an offer price of $54.20 a share, in a <a href="https://www.sec.gov/Archives/edgar/data/0001494730/000110465922045641/tm2212748d1_sc13da.htm">filing </a>to the Securities and Exchange Commission. “My offer is my best and final offer and if it is not accepted, I would need to reconsider my position as a shareholder,” he said at the time. Twitter's shareholder rights plan, which will expire in a year, "does not prevent the board from engaging with parties or accepting an acquisition proposal if the board believes that it is in the best interests of Twitter and its shareholders", the San Francisco-based company said. The plan is "intended to enable all shareholders to realise the full value of their investment in Twitter". It will "reduce the likelihood that any entity, person or group gains control of Twitter through open market accumulation without paying all shareholders an appropriate control premium or without providing the board sufficient time to make informed judgments and take actions that are in the best interests of shareholders", it added. Meanwhile, funding for the Bluesky initiative would need to be re-assessed if ownership of Twitter changed, <a href="https://www.thenationalnews.com/business/money/2021/11/30/what-is-jack-dorseys-net-worth/" target="_blank">Jack Dorsey, founder of the social media platform</a>, said in a tweet. “Twitter doesn’t own it,” Mr Dorsey wrote in response to a comment about Bluesky. Still, “funding would need to be reassessed”. Progress on Bluesky has been slow, he said. The initiative is aimed at developing a protocol to enable multiple social networks to interact.