RE: Adage capital shorting this3 Oct 2023 12:55
I believe it's FTSE rules. They have spoken about it on multiple conference calls and the restrictions and Rusty joked about buying back the entire company at one time.
RNS 27th Jun 2023
"Under the Programme, the Company, at its discretion and on occasion, may (subject to applicable law) purchase its Shares in open market transactions depending on market conditions, share price, trading volume, and other factors."