Japan’s brokerage industry is aiming to identify accounts owned by phishing scammers after fraudulent trades worth more than $4 billion rattled the nation’s stock market.

A Japan Securities Dealers Association panel is looking to start discussions on whether and how member brokers can identify and act against offenders’ accounts at its upcoming annual meeting, said people familiar with the matter, asking not to be named because the issue is private.

The JSDA’s Internet Brokers Council, which comprises about 30 of the nation’s major brokers, is weighing inviting officials from the Tokyo Stock Exchange and police to hear how they are planning to tackle the problem, they said.

Criminals started hijacking online brokerage accounts in Japan and using them to drive up penny stocks around the world earlier this year. The trend peaked in April and has been tapering off. Through July, there were over 8,000 fraudulent transactions, totaling about ¥620.5 billion ($4.2 billion).

A spokesperson from the association, which represents more than 250 brokerages, declined to comment.

The move may signal a new phase in Japan’s fight against hackers. The scams unnerved industry and government officials working to persuade households to invest, but the debate so far has focused on strengthening consumer protection as well as compensating victims.

The Internet Brokers Council, which includes Japan’s largest brokerage Nomura and the country’s biggest online securities house SBI, will soon decide its official agenda for the year ending June 30, the people said.

Planners are making arrangement to add to the agenda a discussion on how brokers can identify perpetrators’ accounts and what steps they can take if they do, including account suspensions, they said.