Parent firm Japan Post Holdings Co plans to sell 975.4 million shares of the banking unit, with an overallotment of an additional 113.6 million shares in the domestic market.

The sale, the first since its 2015 listing, will reduce the parent's stake in Japan Post Bank to 60% from the current 89% to meet new rules requiring companies on the Tokyo bourse's prime section to keep a tradable share ratio of 35% or more.

Japan Post Bank shares closed at 1,155 yen on the Tokyo Stock Exchange on Monday.

($1 = 134.6200 yen)

(Reporting by Makiko Yamazaki; editing by Muralikumar Anantharaman and Jason Neely)