CK Hutchison is backing an all-stock C$23.6 billion (US$18 billion) merger between its unit Husky Energy and Cenovus Energy as the Canadian oil and gas producers seek to end a trail of losses from a slump in global oil prices.The Hong Kong unit, run by Victor Li Tzar-kuoi, will sell its 40.19 per cent interest in Husky to Cenovus in return for a 15.7 per cent equity stake in the combined entity, according to a joint announcement on late Sunday. Husky shareholders will receive 0.7845 of a…