DTR 5.5 Acquisition or disposal by issuer of shares
An issuer of shares must, if it acquires or disposes of its own shares, either itself or through a person acting in his own name but on the issuer's behalf, make public the percentage of voting rights attributable to those shares it holds as a result of the transaction as a whole,1 as soon as possible, but not later than four trading days following such acquisition or disposal where that percentage reaches, exceeds or falls below the thresholds of 5% or 10% of the voting rights.
Additional requirements in relation to a listed company which purchases its own equity shares are contained in LR 12.4.6 R.