Nearly one in three of the 400 largest public companies headquartered in California — including household names Apple, Callaway Golf and Skechers USA — have no women at the top, according to a study released this week by UC Davis researchers.

At the other end of the spectrum, five firms, led by the Los Angeles-based Nara Bancorp, have women in 35 percent to 46 percent of their top posts.

The third annual UC Davis Study of California Women Business Leaders found that 122 of the 400 surveyed companies — 30.5 percent — listed no women executives or board members in their annual reports to the Securities and Exchange Commission. Telecommunications, electronics and semiconductors were the most male-dominated industries. Silicon Valley and Orange County had the highest concentrations of male-dominated firms.

The research was made public at the Sacramento Convention Center on Oct. 16 during the annual conference of the San Francisco-based Professional BusinessWomen of California.

Overall, women held 10.4 percent of board seats and executive positions, virtually the same as the 10.2-percent figure reported in 2006 and 2005. Three percent of the surveyed companies had female chief executive officers, also representing no increase from the previous studies.

"Too many board rooms and executive suites in California still look more like 1957 than 2007 in terms of gender equity. And we've seen no real change in three years," said Nicole Woolsey Biggart, dean of the UC Davis Graduate School of Management, which conducted the study in partnership with the Palo Alto-based Forum for Women Entrepreneurs and Executives.

Leading the state in gender diversity was a Los Angeles-based firm, Nara Bancorp, which serves consumers and minority-owned businesses through nearly 20 branches in Korean districts in California and New York. The study found that 46.2 percent of the company's executive and board seats are held by women.

"We have created a culture where people know that those who are aggressive and deliver will rise to the top, regardless of age, gender or other factors," said Min Jung Kim, president, CEO and board director of Nara Bancorp. "That culture attracts and allows us to keep top talent, and is at the root of our company's success."

Joining Nara Bancorp in the top five companies were San Francisco-based Bare Escentuals, with women in 45.5 percent of the top spots; Bebe Stores, headquartered in Brisbane, at 43.5 percent; Hot Topic, based in City of Industry, at 36 percent; and San Diego-based Jack in the Box, at 35 percent.

In all, 25 companies with the highest percentages of women in top leadership positions received awards during a luncheon at the Professional BusinessWomen of California conference.

"We're proud to honor companies with the wisdom to recognize the value of placing highly qualified women in such positions," said former California state Sen. Jackie Speier, founder of Professional BusinessWomen of California.

In the 2007 and 2006 studies, UC Davis researchers used Standard & Poor data to identify the top 400 companies headquartered in California by net revenue. The researchers, led by associate finance professor Katrina Ellis, then compiled information about the company directors and top executives from the firms' Securities and Exchange Commission filings.

Top executives, defined as members of the companies' executive teams in their SEC filings, typically included the CEO or president, chief financial officer, chief information officer and chief operating officer. Some companies also included corporate counsel, the head of human relations and executive vice presidents.

The first study, in 2005, looked at half as many companies and only the top five highest-paid executives at each company.

The studies from 2005 through 2007 are available at www.gsm.ucdavis.edu/census.