Twitter announced Friday that its board of directors unanimously approved a “poison pills” defense to respond to Elon Musk’s offer to buy the company and make it private for $43 billion.

This would enable existing Twitter shareholders (except for Musk) to purchase additional shares at a discount. It would dilute Musk’s stake and make it more difficult for him to win a majority shareholder vote in favor of the acquisition.

Twitter’s plan will take effect if Musk’s approximately 9% stake rises to 15% or higher.

The poison pill adds another layer to , a drama about the possibility that the world’s wealthiest person could take over a social media platform. He described Thursday as the “de facto square” of the world.

Twitter claimed that its plan would decrease the chance of any individual gaining control of the company. It did not pay shareholders a premium nor give the board more time for an offer to be evaluated. These defenses are also known as shareholder rights plans. They prevent hostile takeovers by making acquisitions prohibitively expensive.

Musk could still take control of the company even if it discourages him from trying to takeover the company. He could do so by engaging in a proxy fight, where shareholders vote on whether or not to keep the current directors. Twitter stated that its plan does not prevent the board from accepting or negotiating an acquisition proposal if it is in the company’s best interest.

Daniel Ives, analyst at Wedbush Securities, said that “they’re getting ready for a fight here with Musk.” They also need to allow themselves to search for another buyer.

Musk offered to buy the company for $43 billion. He said that the company “needs” to be “transformed as a private business” to gain trust from its users and better serve what he called the “societal imperative” to free speech.

During an interview on Thursday at a TED event, he stated that “having a public platform which is maximally trustworthy and broadly inclusive is extremely crucial to the future civilization.” He spoke just hours after his bid was announced.

Musk, who has over 82 million followers on Twitter, is both a frequent user and vocal critic of Twitter’s measures to limit accounts that spread misinformation and encourage violence and hate speech. Musk said Thursday that he opposed permanent user bans, the most well-known being the suspension of the account of former President Donald Trump by Twitter after the Jan. 6, Capitol riot.

Recent regulatory filings revealed that Musk had been purchasing Twitter shares almost daily since Jan. 31 and ended up with about 9%. Only Vanguard Group has more Twitter shares. A lawsuit was filed Tuesday in New York Federal Court alleging that Musk unlawfully delayed disclosing his stake to the social media company in order to buy more shares at lower prices.

Twitter offered Musk a seat on its board immediately after Musk declared his stake. However, he was required to limit his purchase of stock to 14.9%. Five days later, the company informed Musk that he had declined to take part.

Ives stated that Twitter’s poison-pill path is a predicable defensive move, but could also be seen as a sign of weakness for the company on Wall Street.

Musk could attempt to challenge the measure in court. However, John Coffee, Columbia University law professor, said that “no court has overturned any poison pill in 30 years.” Coffee stated that rallying shareholders to expel the board may be easier but poses challenges for Musk.

Musk’s offer was already met with resistance by Twitter before it was counterpunched on Friday.

In a Thursday tweet, a Saudi prince, who is one of Twitter’s largest shareholders, mocked Musk’s offer. Al Waleed bin Talal stated that he would not accept Musk’s offers because he doesn’t believe $43B “comes close” to Twitter’s intrinsic value given its growth prospects.

Musk’s $54.20-per share offer is almost 40% higher than Twitter’s stock price prior to he revealed his massive investment. However, it’s still well below the $77.63 peak closing price reached less than 14 month ago. Twitter was worth $62 billion at that point.

Musk replied to the prince by tweeting to ask how many Twitter shares they have. He then made what might have been a veiled reference the 2018 murder of Jamal Khashoggi, which was linked to Saudi Arabia’s Crown Prince Mohammed bin Salman. Musk tweeted on Thursday, asking “What is the Kingdom’s view on journalistic freedom-of-expression?”

Twitter stock dropped in the first trading day after Musk’s takeover offer was made. This is a clear sign that investors are not convinced. Friday’s Good Friday holiday saw the stock markets close. Twitter stated that it will disclose additional details about its shareholder plan in a future regulatory filing.

Mark Cuban (Dallas Mavericks owner, tech investor) also shared his theories on Twitter that Musk is trying to increase the stock price of the company so he can make a profit. Cuban, who used a profane term to suggest that Musk is also using the bid for revenge on the U.S. Securities and Exchange Commission. This agency was fined $20 million by Musk in 2018, after he tweeted about a possible buyout of Tesla.

Musk made clear that he still has a problem with the SEC at Thursday’s TED conference and cursed them with a profanity.