Activist investors’ infatuation with Japan has reached record levels. So has their influence.

The funds have bought at least ¥1 trillion ($6.6 billion) worth of Japanese stocks this year, according to data compiled by Bloomberg Intelligence. Even after taking into account the deals they exited, their net buying is likely to be more than ¥500 billion.

That makes them the largest purchasers of the country’s equities after companies doing stock buybacks.