Best Buy's new female CEO will join a growing -- but still minuscule -- club

A small club of powerful women is about to get a little bigger.

With news that Best Buy named Corie Barry its new CEO, the number of women CEOs at S&P 500 companies will grow to 26 by the time Barry takes office in June, according to the latest count from nonprofit research group Catalyst. Those 26 women CEOs will represent just 5.2% of all S&P 500 CEOs.

Barry will also join Best Buy's board, which will expand to 13 directors.

Currently Best Buy's chief financial officer, Barry will become the company's 5th CEO and its first woman chief executive. She's replacing Hubert Joly, who will step into the newly-created role of executive chairman of the company's board of directors.

For an incoming CEO, Barry is fairly young, turning 44 this week. By comparison, the median age when men and women are appointed CEOs is roughly 55, according to corporate data research provider Equilar.

Barry's appointment is welcome news to those who've been advocating for more women leaders and board directors.

But PSA: We're well into the 21st century and women have been in the workforce for decades.

While women make up close to half of the overall workforce at S&P 500 companies, the percentage of women in more senior roles is much lower. Only about 27% of senior management roles are held by women, while only about 5% of CEOs are female, according to Catalyst.

Why the big drop-off?

"There are a lot of cultural issues that we're still dealing with. There's not enough mentoring and sponsoring of women to make sure they get the 'hot' jobs," said Catalyst president and CEO Lorraine Hariton.

"Hot" jobs are primarily revenue-generating, growth-driving positions that provide people with the skill sets and visibility that are more likely to put them on the CEO track.

Women who do make it to the C-suite typically take the non-revenue generating roles in finance, marketing or human resources, Hariton noted.

Also, she added, there remain unconscious biases and stereotyping of women in the workplace, as well as a "Goldilocks syndrome." For instance, a woman risks being seen as either too assertive or not assertive enough for a given role. In other words, "she has to be really perfect to move ahead," Hariton explained.

In Barry's case, she came up through the finance channel but also served in some operational roles at Best Buy along the way, including a stint as its chief strategic growth officer.

The good news is that by all indications Barry was groomed for the CEO spot, Hariton said.

And there's a growing understanding today that companies that make a concerted effort to advance women leaders do better financially and competitively, she added.

- CNN's Nathaniel Meyersohn contributed to this report.