Message : Required fields (Reuters) - China's Ant Group, the fintech giant whose $37 billion IPO was derailed by regulators days before it was due to list in November, is to restructure as a financial holding company. The overhaul comes just after e-commerce giant Alibaba Group Holding Ltd, of which Ant is an affiliate, was hit with a $2.75 billion antitrust penalty as China tightens controls on the "platform economy". The Alibaba business empire has come under intense scrutiny in China since its billionaire founder Jack Ma's public criticism of the country's regulatory system in October. Following are key events leading up to Ant Group's shift to a holding company and the fine on Alibaba.