After cornering the bond market, the Bank of Japan has its sight on the stock market with a Record Buying Binge in March.

The Bank of Japan spent 833 billion yen ($7.8 billion) on exchange-traded funds tracking the country's shares last month, the largest amount ever according to data back to 2010. The BOJ stepped in as the Japanese market slumped and its benchmark Topix index inked its first back-to-back monthly declines since the start of 2016. Haruhiko Kuroda's bank is now ahead of its scheduled goal to spend about 6 trillion yen a year on ETFs. "If the market keeps on falling, there will be the problem of what they do next," said Kazuyuki Terao, chief investment officer for the Japan arm of Allianz Global Investors.