NEW YORK (BLOOMBERG) - In the United States, people whose family origins trace to a vast swath of the globe are lumped under the demographic category of "Asian".

Members of the group do not have much in common, with one exception: They tend to be notably absent at the highest levels of corporate America.

Across America's big corporations, Asian Americans get hired at a much higher rate than their proportion of the general US population, which is about 6 per cent. The group makes up more than 20 per cent of the student body at some of the elite colleges and universities that shoot graduates up the corporate ladder - and a recent lawsuit suggests that percentage could be a lot higher.

And yet, Asians are hardly promoted at the same speed as their white colleagues.

"We are the most successful minority," said Mr Buck Gee, a retired Cisco Systems vice-president and co-author of a new report about Asian leaders in the technology industry for the non-profit Ascend Leadership. But when the lens turns to C-suites and upper management, "we're the least successful minority".

Asians held 47 per cent of professional jobs in Silicon Valley tech companies in 2015, slightly more than white people, according to Equal Opportunity Commission data analysed by Ascend. But at top levels, Asians were far outnumbered, holding 25 per cent of executive positions, compared with nearly 70 per cent held by white people.

In US private companies, Asians make up 12 per cent of professionals and 5 per cent of executives, according to EEOC data.

In finance, the numbers tell a similar story.

Goldman Sachs Group is typical: a quarter of professional employees are Asian, but fewer than 11 per cent of executives and less than 1 per cent of the management committee are.

Ms Leslie Shribman, a spokesman for Goldman, said the company's success depends on attracting diverse employees and pointed to programmes that support Asians, including one designed to "develop the next generation" of Asian leaders.

Representatives of other financial institutions also said they were keen on increasing Asian numbers; Citigroup spokesman Elizabeth Kelly said the bank had recently revamped its diversity strategy to recruit and develop more Asians and members of other underrepresented groups.

The absence of Asians in senior leadership poses a challenge to advocates for racial and ethnic diversity within big corporations. The lack of black people and Latinos in upper-level jobs is often described as "a pipeline problem" - a lack of diversity in the junior or mid-level positions - and in response, some companies have increased their recruiting efforts with black and Latino college graduates.

There are lots of Asian people in professional and middle management roles, said Ms Jane Hyun, a diversity consultant who coined the term "bamboo ceiling". Because of their success in getting hired, she added, "Asians were missing from the whole diversity conversation".

Ms Ellen Pao, who is perhaps best known for her gender discrimination lawsuit against her former employer, venture capital firm Kleiner Perkins Caufield & Byers, said racial bias was prevalent in Silicon Valley, too.

In her recent book, "Reset: My Fight For Inclusion and Lasting Change", she writes that her boss in Silicon Valley often confused her with another Asian woman who had previously held her job. She also frequently heard jokes and ethnic stereotypes about Asians.

There are more than a few Asian Americans running big companies. They include Microsoft's Satya Nadella; Google's Sundar Pichai; Berkshire Hathaway's Ajit Jain, the head of reinsurance; and Citigroup's chief risk officer Brad Hu.

Success stories can make the imbalance seem less severe than it is, said assistant professor of management Laura Huang at the University of Pennsylvania. "If we look at ratios in the population versus top management, it's very skewed - it's not proportionate."

Ascend's Mr Gee, and Mr Wesley Hom, a retired IBM executive, worked with Stanford University to develop a course to help Asian managers break through to the upper levels. Classes in the week-long, US$12,600 (S$17,069) programme are drawn from the general executive curriculum at Stanford's Graduate School of Business.

They also address behaviours that, as Mr Gee's research shows, can slow a career and tend to be more common among people of Asian heritage, including deference to authority and an aversion to risk taking.

"My brother and I were raised to not talk unless we were spoken to," said Mr Wes Chung, 40, who works as the chief of staff for IBM's chief brand officer. "We were told to work hard and the results would come to you."

Mr Chung took the Stanford class which, he said, helped him be more assertive about his ambition.

Encouraging people to assimilate cannot be the only solution, said Ms Hyun, whose book "Breaking the Bamboo Ceiling: Career Strategies for Asians" was published in 2005.

"That's putting the onus on one party. If nobody is meeting you part way, it becomes very stressful," she said.

Ms Pao now runs an organisation, Project Include, that advises companies on steps they can take to promote equitable treatment of all employees. "Putting it on the employee to change their behaviour is not going to solve the problem," she said.

"This kind of solve-one-problem-at-a-time approach creates divisions among groups that should be working together."