A statement from PCP3, an investment vehicle connected with the investor, who also owns Manchester City Football Club, revealed that it had completed a derivatives deal involving the shares.
Investment bank Nomura is selling the 220 million shares on behalf of PCP3 at a price ranging from 290p to 295p each.
PCP3âs remaining 131.6 million shares in Barclays will be exercised into stock by the firm.
The release from PCP3 said: âThe exercise and hedging mark the final completion of a strategy that locks in a significant gain on Barclays PLC shares for PCP3 while retaining further upside.
âPCP3 will seek to continue to maintain a close commercial and strategic relationship with Barclays in the future."
Sheikh Mansour was one of a number of investors from the Middle East who used their capital to prop up Barclays during the global credit crisis.
By Jim Ottewill