Japanese civil engineering group Infroneer said on Tuesday it would buy Japan Wind Development from Bain Capital for about $1.4 billion — an acquisition that will expand its renewable energy business.

Japan Wind Development says it operates 293 wind turbines, the vast majority in Japan, with a combined generation capacity of 570,850 kilowatt hours. It is the country's market leader for maintenance of wind power generators, Infroneer said.

The deal is expected to close in late January.

The sale was made through a competitive bidding process, a person familiar with the matter said, declining to be identified.

Bain Capital, which led a management buyout of Japan Wind Development in 2015 for ¥9.7 billion, declined to comment.

Reports of the acquisition costs sent shares in Infroneer sliding 6% on Tuesday.

Renewable assets have become increasingly attractive as Japan seeks to transition to a zero-emission economy.

Mergers and acquisitions involving Japanese companies in the renewable energy sector have climbed more than eight times to $1.8 billion for the year to date from the same period a year earlier, marking the highest level since 2019, LSEG data showed. The number of deals at 28 is a record high.

Infroneer has worked on two wind farms in northern Japan which have since been sold.