Japanese auto giants Honda and Nissan are in preliminary merger talks to compete with Tesla and Chinese electric carmakers.
Taiwanese tech giant Foxconn - formally known as Hon Hai Precision Industry - has approached Nissan to acquire a controlling stake.
Nissan's shares rose as much as 24 percent, while Honda's fell more than 2 percent. Mitsubishi Motors, whose main shareholder is Nissan, reported a 13% rise.
Japan's second- and third-largest automakers after Toyota agreed in March to explore a strategic partnership in electric vehicles.
"We are discussing opportunities for cooperation... in a wide range of areas and in various fields," a Honda spokesman told AFP.
Major carmakers around the world are facing stiff competition in electric vehicles, particularly from Chinese rivals such as BYD.
Volkswagen, for example, is considering closing German plants for the first time in its history.
Last month, Nissan announced 9,000 job cuts, slashed its sales forecasts and said it would reduce its global production capacity by 20%.
Warning of the "grave situation", CEO Makoto Uchida forfeited half his salary.
Nissan has endured a tumultuous decade that included an attempted grand alliance with France's Renault, for which its former boss Carlos Ghosn was arrested in 2018 | BGNES