Honda Motor and Nissan Motor are exploring a merger to create one of the world’s largest auto groups as they seek to better position themselves for the expensive technological transition reshaping the automotive industry.

On Monday, Honda and Nissan signed a memorandum of understanding to formally begin talks aimed at deepening a partnership that began this year. Over the next six months, the companies will discuss combining their operations under a holding company, with the goal of completing the merger in August 2026.

Honda and Nissan, Japan’s second- and third-largest automakers, would join a growing number of legacy auto giants, including General Motors and Volkswagen, that are deepening ties to share the financial burden of developing next-generation vehicles. The deal is seen as a lifeline in particular for Nissan, which has been slashing jobs and production amid faltering sales.

Unlike the gasoline-powered cars that have defined the industry for most of the past century, more vehicles today are being equipped with batteries, electric motors and advanced software that enables features such as autonomous driving.

To navigate the change, Honda and Nissan have decided they can better handle research and development and new investments as a combined force, Honda’s chief executive, Toshihiro Mibe, said at a briefing in Tokyo on Monday.

“Current business models are being upended. It is not going to take 10 to 20 years for that to happen — it will come much faster,” Mr. Mibe said. “We need to have the right artillery in order to be competitive on that battlefield so we’re starting today.”