Two private equity firms, Carlyle Group and Bain Capital and Mahle, an auto supplier, offered to acquire a 70% stake in Hanon Systems, a thermal and energy management solutions provider, from Hahn & Co, a private equity house, and Hankook, a company engaged in automobile parts industry, for $5.8bn. Hanon Systems, the world’s second-largest supplier of auto thermal management systems, reported revenue of $6.08bn and operating profit of $278m last year.