Japanese automakers Nissan and Honda were expected to announce Monday that they are in talks on a merger that would catapult them to No. 3 in a global industry undergoing tectonic shifts as it transitions away from reliance on fossil fuels while facing intensifying competition from Chinese rivals. The two companies, and smaller Nissan alliance member Mitsubishi Motors, said their top executives would hold a news conference later in the day. Local media including Kyodo News Service and broadcaster NHK said the companies’ boards had held meetings and top company executives had informed relevant government ministries that they plan to have details finalized by June.