Women changing Silicon Valley from the top

What does it take to move the needle when it comes to women holding the top roles at tech firms?

For the first time, Watermark, an organization of Bay Area female executives focused on increasing women in leadership, produced the Watermark Index, as part of UC Davis' annual study on women in business leadership. To qualify, women have to make up more than 30 percent of a public company's directors and its five highest-paid executives. Only 4.9 percent of the Bay Area's 233 biggest public companies by market capitalization made the cut.

The index's purpose is to highlight the best firms in the Bay Area when it comes to female leadership and spur other companies, and entire sectors, to do better on gender diversity, said Marlene Williamson, Chief Executive of Watermark. "When you have a female in a leadership role, it tends to permeate the entire industry," she said. "Change is faster when there is a woman at the top."