Asian markets had a wild start to the week, with Tokyo’s Nikkei 225 index tumbling nearly 5% while Chinese markets soared on news of fresh stimulus for the faltering economy, with Shanghai up more than 7%.

Stocks dropped after Japan’s governing party chose Shigeru Ishiba, a critic of the country’s longstanding ultralow interest rates, as its leader.

Japan's incoming prime minister Shigeru Ishiba is poised to call snap elections for October 27, local media reported Monday, as equities plunge on a strong yen and fears that tax hikes are on the cards.

Shares in Tokyo fell sharply Monday, on concerns that Japan's next prime minister could adopt policies that wouldn't be very friendly to the economy and markets. The benchmark Nikkei Stock Average fell 4.