Four companies headquartered in Singapore have been recognised in a global index for their commitment to transparency in gender reporting and advancing gender equality.

Singtel, United Overseas Bank (UOB), City Developments (CDL) and DBS Group Holdings made it to the second edition of the Bloomberg Gender-Equality Index, which was released last week.

CDL and DBS were also in the inaugural index last year.

The 2019 list includes 230 firms headquartered across 36 countries and regions.

Ms Chua Sock Koong, group chief executive of Singtel, said women represent a third of staff and management across the group and on its board.

"(Diversity) allows us to tap... fresh perspectives and creativity which are critical to building a vibrant, successful and sustainable organisation," she said.

UOB deputy chairman and group chief executive Wee Ee Cheong also said that differences in qualities, capabilities and experiences among colleagues help them appreciate and connect with customers.

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The index is based on a reporting framework Bloomberg created for companies to voluntarily disclose information on how they promote gender equality across four areas: company statistics, policies, community engagement and products and services. Those that score above a globally established threshold are included in the index.

Data collected for the latest index showed that, among the 230 companies, women were well represented in some areas.

They received 43 per cent of promotions, on a par with their composition of the total workforce at 42 per cent. But they made up only 7 per cent of chief executive or chair positions, and 26 per cent of senior management roles.