Analysts seem to love to talk about a "Marissa Mayer effect."
When Yahoo's stock leaped in the year after Marissa Mayer took the helm as president and CEO, many believed it was partly due to her glamour. Later, when the stock slipped, it was owed to her pregnancy.
But as it turns out, there may not be much of a Marissa Mayer effect at all: One of the major reasons behind Yahoo's uptick in the beginning was largely driven by the company's Alibaba deal; the recent decline in the stock price coincided with China's turmoil. And while Mayer has failed to turn Yahoo around, the three previous CEOs failed, too.
But a growing number of investment experts believe not in the power of a single woman CEO but in what could more broadly be called a woman effect: the idea that women-led companies, or at least those with women in management, as a class perform better over time.