Twitter shares rise 4% as Musk keeps up his barrage by tweet 

The social media company launched a so-called poison pill defence to thwart Musk's unsolicited bid

Elon Musk has been actively posting on his Twitter account in what appears to be a social media campaign to sway public opinion in favour of his bid.

Twitter shares gained on Monday after the social media company launched a so-called poison pill defence to thwart an unsolicited bid by Elon Musk to take the company private for $43bn (€39.7bn), or $54.20 a share.

A securities filing has confirmed the defence strategy Twitter outlined last week, which would allow the company to issue new stock that all shareholders except Mr Musk would be able to buy at a discounted price. It imposes a “significant penalty” on any person or entity that would acquire more than 15% of the company without board approval, according to the filing. Mr Musk currently owns just over 9% of Twitter shares.