Television maker Hisense Group Holdings’ optical communications unit made a steady debut in Hong Kong after raising HK$5.6 billion (US$714 million), adding momentum to a fresh wave of mainland Chinese conglomerates spinning off business units to tap overseas capital and support technology expansion. Shares of fibre-optic communications equipment maker Ligent Technologies jumped as much as 19.2 per cent on Tuesday morning, valuing the company at more than HK$35 billion. The stock pared early...