And while much has been written about their financial handicaps—lower pay, shorter time in the workplace, lack of access to a retirement plan, risk aversion in investments—not all that much attention has been devoted to gearing education about retirement savings to those particular issues and needs.

Women, after all, are working harder at saving for retirement than men, according to an ADP Research Institute study, for all the good it's doing them.

Parity between women and men in the financial services industry could conceivably lead to products that are more suited to compensating for the issues that women face, while a better understanding of those issues could lead to better ways to educate women on the aspects of retirement planning in which they lack confidence.

The 2017 index includes only 52 firms across Europe, the Middle East and Africa (EMEA), Asia Pacific (APAC) and the Americas. The BFGEI provides managers and investors with more comparative information across the gender-equality space, while encouraging disclosure, providing greater market transparency and raising awareness of gender-related issues.

Voya said that its presence in the index "showcases its commitment to creating an environment of inclusion and, alongside its peers recognized in the BFGEI, its commitment to better understanding the gender-equality issues that customers, colleagues and communities face."

The index is scored via a social survey developed by Bloomberg in partnership with third-party experts that include Women's World Banking, Catalyst and Working Mother Media. To be included in the index, companies must have dedicated social disclosure policies and practices.