Gender pay gap disclosure is now mandatory for Japan firms with more than 300 employees, but some investors say improvements are needed for the data to be useful for investment decisions.

Some businesses have disclosed pay gaps according to different job levels, but for the most part companies are revealing the minimum amount of information necessary.

Under the government’s requirements, firms have to disclose the pay gap for the three categories of all employees, regular and nonregular workers. The data is calculated from the average annual wages of female and male employees, and shows what percentage of men’s salaries women are paid.