According to a July 31 filing with the Securities Exchange Commission (SEC), bitcoin miner Riot Platforms stepped up its acquisition strategy against rival Bitfarms this month by purchasing about 10 million additional shares. Riot currently holds 71.56 million of Bitfarms' total outstanding shares, valued at $159.10 million, or a 15.9% stake in the Canadian miner, according to the SC 13D/A filing. The acquisition came shortly after an Ontario capital markets tribunal ruled that Bitfarms' original shareholder rights plan, which stipulated dilution of outstanding shares if any one entity acquired more than 15 per cent of the company, was invalid. Before that ruling, Riot held a 14.9 per cent stake in Bitfarms.