Yahoo's Marissa Mayer is a reminder that CEO is still elusive for women

The Yahoo CEO's inevitable resignation raises the questions: do women get a fair shot at reaching the corner office? And are they treated equally once they do?

In the same week the United States gained its first female presidential nominee for a major political party, the country also lost one of its highest-profile female CEOs, with the announced $4.8bn acquisition of Yahoo's core assets by Verizon.

When - and it looks inevitable - Marissa Mayer steps down from Yahoo, she will lose her status as head of part of a tiny and elite group of women who head publicly traded companies.