One American company called Strategy owns more than 3% of all bitcoin in existence. Its executive chairman, Michael Saylor, is the pioneer of a new business model where publicly listed companies buy cryptocurrency assets to hold on their balance sheet. Strategy, formerly called MicroStrategy, first bought US$250 million (£187 million) worth of bitcoin in mid-2020 during the depths of the COVID economic slump. As it continued to buy bitcoin, its share price soared, and it kept buying.