Cynthia Carroll's departure from the helm of mining company Anglo-American didn't just affect the company's share price—it sparked a new round of questions about the lack of women in the top echelons of the business world.
Carroll's exit means that the number of women at the top of FTSE 100 companies has halved within a month, after Dame Marjorie Scardino announced her departure from Pearson . Alison Cooper at Imperial Tobacco and Angela Ahrendts at Burberry will shortly be the only women leading major London-listed companies.
Of course, both women have their individual reasons for stepping down and neither appears to be related to gender issues. Scardino's 15 years at the top of Pearson were probably due to come to a close soon—she turned 65, the official U.K. retirement age, this year—while mother-of-four Carroll is in charge at a difficult time for her company and the mining industry.
Neither has sought to be emblematic of their gender, but unfortunately, as there are so few women at the highest level of the business world, it is difficult to avoid—as anyone who saw the coverage of six-months pregnant Marissa Meyer's appointment as chief executive of Yahoo can attest.
This week has already seen tussles at the European Union over Justice Commissioner Viviane Reding's proposals to enforce a 40 percent quota for women on company boards. Plans have been put on hold after objections from around the EU—including from some of its most influential women. Norway imposed similar quotas in 2003, and now has 42 percent female representation on company boards.
- Read More: EU Drops 40% Women in the Boardroom Plan
"There is obviously pressure from everywhere, especially politics, to increase diversity on boards. It's de facto a good thing. Diversity at board level is a good thing for companies," Bob Parker, senior adviser at Credit Suisse, told CNBC. He added that there are "very powerful arguments" not to have a quota system.
Between 2005and 2011, the share price of companies worth more than $10 billion with women on their boards outperformed comparable companies with all-male boards by 26 percent, according to research by the Credit Suisse Research Institute. Companies with a woman on the board had lower debt-to-equity ratios and started reducing their debt more quickly at the start of the credit crisis.
Yet women are still significantly under-represented on boards around the world.
One reason for this may be found in education. While women outperform men at most earlier educational levels, when it comes to MBA time, only half as many women as men get those three letters after their names. This may be because MBAs are often done in the late twenties, when people of both genders are starting to think about marriage and children.
- Read More: Women's Pay Gap Starts Right After College: Study
Yet the pay gap has already started by this stage. In the U.S., the median female wage is only 81 percent of the median male wage. This operates across class and education boundaries, with female graduates earning 82 percent of their male counterparts' wage within a year of graduation, according to the American Association of University Women.
Whatever is preventing women getting their feet under the boardroom table, it seems unlikely to be solved soon.
—By Catherine Boyle, Staff Writer, CNBC.com