Japan's incoming prime minister, Shigeru Ishiba, will fill key party posts on Monday and announce a new Cabinet on Tuesday as he tries to unite an LDP party split by one of its closest ever leadership races ahead of a likely snap general election.

STORY: Japan’s incoming prime minister, Shigeru Ishiba, said Monday (September 30) he's calling a snap general election on Oct. 27.He just won a close leadership race to become head of the ruling Liberal Democratic Party.

Japan’s benchmark Nikkei 225 index tumbled nearly 5% early Monday after the country’s ruling Liberal Democrats chose Shigeru Ishiba, a former defense minister, as the next prime minister. Ishiba is due Tuesday to succeed current Prime Minister Fumio Kishida,