In a document presented to its reform panel on Wednesday, the Tokyo Stock Exchange (TSE) said it would first make mandatory the simultaneous English publication of financial statements and other key items that require timely disclosure.

The rules will be applied to some 1,600 prime-listed companies, starting in April 2025.

"Simultaneous English disclosure of all documents in full is preferred, but it shall be sufficient to disclose in English a part or a summary of the content of the disclosure in Japanese," the TSE said in the presentation.

As of last year, 42.3% of companies on the prime section released their earnings reports in Japanese and English simultaneously, while only 28.5% published other key items in both languages at the same time.

The bourse's reform panel has cited foreign investors as saying that a lack of English disclosure is one of the reasons for staying away from Japan's stock market.

The new rules are the latest of a series of the TSE's reform steps to make the bourse more attractive to overseas investors, including the release this week of a list of companies that have responded to a call to disclose plans to improve capital efficiency.

(Reporting by Makiko Yamazaki; Editing by Mark Potter)

By Makiko Yamazaki