The slowdown stands in stark contrast to the gains made by women in the broader work force. Median pretax income for working-age women more than quintupled between 1962 and 2014, to $20,000. It’s still far below the median pretax income for men, which, at $35,000, has stayed roughly the same since 1964, according to the research paper. (The paper uses “labor income” as its definition of income, which does not include capital gains and certain other sources of wealth.)

The women’s wealth gap would be even worse without inherited fortunes. According to Wealth-X, of the 294 female billionaires in the world, only 49 are self-made. The rest owe their fortunes partly or entirely from an inheritance.

Of the nearly 27,000 women in the world worth $30 million or more, a third are self-made. And there are reasons to think that those numbers could rise, as wealth becomes more global and women in countries like China start to prosper. In 2015, more than half of the female billionaires in Asia were self-made, compared with 19 percent in the United States, according to a report from the Swiss bank UBS and the consulting firm PwC.

Yet even as many women are making the rich lists, others are dropping off. In the United States, one of the highest-flying self-made female billionaires, Elizabeth Holmes, recently became the highest-profile financial casualty: As the medical-testing company she founded, Theranos, started to collapse amid fraud allegations, Ms. Holmes’s net worth plummeted from about $4.5 billion to next to nothing, according to Forbes.

At the moment, the wealthiest self-made woman in the United States is Diane Hendricks, a founder of ABC Supply, a building-materials company in Beloit, Wis. She is worth $4.9 billion, according to Forbes. Oprah Winfrey ranks second at $3.1 billion.

So why are there so few women at the top of the wealth pyramid? And what needs to change?

Julia Pimsleur, the founder of the multimillion-dollar Little Pim language-instruction company and the daughter of the language training entrepreneur Paul Pimsleur, said that discrimination in the executive suite and the world of venture capital remained a stubborn force.

“There is unconscious bias in the system,” she said. “I believe there are many men who would like to see more women at the top.”