Japanese stocks tumbled after Shigeru Ishiba’s surprise victory over Sanae Takaichi in the ruling party’s leadership race wrongfooted investors who had bet on a boost from more monetary stimulus from his rival.

Shigeru Ishida had beaten Economic Security Minister Sanae Takaichi in the final round of the Liberal Democratic Party election on Friday.

Japan’s Nikkei 225 index tumbled by more than 4% on Monday, driven by a combination of underwhelming industrial production figures and the market’s reaction to the election of new Prime Minister Shigeru Ishiba.