Rosneft Oil Co. said Friday that it swung into a net loss for the first quarter of 2020, and that it was launching a buyback program. The London-listed Russian oil company said net loss for the period was 156 billion rubles ($2.12 billion) compared with a net profit of RUB131 billion for the first quarter of 2019. The company said this was due mainly to a foreign-exchange loss of RUB177 billion due to the depreciation of the ruble and revaluation of foreign-currency financial liabilities.