"I believe this is in the best interests of all. If the merger is successful, I am confident that there are good prospects for the enlarged Sandon," he said.
Sandon Capital is an Australian-base "activist" investment firm, according to his website.
"We devise and implement active engagement strategies that seek to unlock value inherent in listed companies, securities and trusts in our investment portfolios," it said.
Sandon woud continue to be an activist investor under the chairmanship of Gabriel Radzyminski, Brierley said.
Brierley last week sold sold his 18.8 per cent of his stake in Mercantile to Sandon Capital, in return for Sandon shares. He remains the biggest shareholder in both companies.
Ron Brierley founded the much feared corporate raider, Brierley Investments, in 1961.
He went on to capture investors' imaginations with some daring market plays, which often bore fruit for shareholders, in the market boom years of the 1980s.
Then came the crash of 1987, from which the company never really recovered.
Brierley retired as a director of the company he founded in 2001.
Brierley was chairman of another corporate raider come investment company, Guiness ness Peat Group plc (GPG) in 1990 where he also applied his investment approach.
GPG was renamed Coats PLC in 2015. Brierley stepped down as a director of Coats in 2015.
