Women remain a rarity in the top echelons of corporate Canada, a study from executive search firm Rosenzweig & Company shows. It found just four of the chief executives at Canada's 100 biggest public companies are women and only 7.4% of the more than 500 senior executives at these companies are women.

Slight progress seems to have been made in recent years. The percentage of top-level executives that are women has risen from 6.9 since the same study was done last year, and it was just 4.6% in the inaugural report in 2006.

"The pace of change is disheartening," said Michelle Morin, a partner at Rosenzweig. "In the past six years we've been studying this issue, and very little has improved for talented women executives."

To make matters worse, Nancy Southern holds two of the four top chief executive positions -ATCO Group and affiliated company Canadian Utilities Ltd. In 2006, she was the only woman among CEOs at Canada's biggest companies. The other women CEOs noted in the report were Kathy Bardswick of the Co-operators Group Ltd. and Sophie Brochu of Gaz Metro Ltd. Partnership.

"We don't think that any type of gender bias is institutionalized. We don't even think it's necessarily conscious," said Alan Zelnicker, a partner at Rosenzweig. "People tend to hire like-minded or similar people. . So until the power structure changes, you're going to have men tending to hire more men."

Ms. Bardswick said another factor is women are not vying for these positions as much as men. "We are not as aggressive in putting ourselves out there," she said. "We don't fight hard enough for what we think we need. Females need to be more aggressive about putting their capacity and interests forward."

Moral arguments aside, Mr. Zelnicker said it's in companies' best interests to include more women and members of various demographic groups among their key decision-makers. He said studies have shown companies with more women in their executive ranks perform better on stock markets.