As if the persistent wage gap between women and men weren’t enough, women have also been disproportionately hammered by the wave of job losses hitting US retail.

Between October 2016 and October 2017, the retail industry lost 54,300 jobs, according to an analysis of data from the US Bureau of Labor Statistics by the Institute for Women’s Policy Research (IWPR). That net decline is tied directly to the jobs lost by women. During that period, women lost 160,300 jobs, while men actually gained 106,000 jobs.

The analysis looked back at retail employment since just before the recession in 2008. Generally, changes in the number of jobs held by men have preceded a similar trend for women. Men’s employment started to fall in 2007, and then women’s followed. Men’s employment then rebounded in 2010, and women’s picked up after. But 2017 has diverged completely from that pattern.

The IWPR first noticed the trend last year and started tracking it. “Now we have a year of data,” Heidi Hartmann, an economist and president of the IWPR, tells Quartz, “and it’s quite pronounced.”

“It’s like women got coal in their stockings for Christmas,” she adds.

The why is not immediately evident

By far the majority of losses for women and gains for men happened in general-merchandise stores, which include warehouse clubs and all those struggling department stores. Within that category, women lost 161,000 jobs while men gained about 88,000.

Hartmann suspects that these stores are selling more durable goods, such as home appliances and home-repair products, but fewer items like clothing and cosmetics. The reason that could cause a gender gap in job losses is that women have historically held positions in departments such as clothing and cosmetics, while those selling the big-ticket items are staffed by men.

This discrepancy was at the center of a series of sex-discrimination cases in the 1970s and ’80s, because those sales generally earned a sales associate a commission. The US Equal Employment Opportunity Commission argued that women were not being hired or promoted into commission-earning sales jobs as often. Many corporations settled out of court, but Sears fought back. “The paucity of women in the higher-paying commission sales jobs, Sears argued, was not due to discrimination but rather to women’s preference for less competitive jobs,” the New York Times reported in 1986, when a federal court ruled that Sears was not guilty of sex discrimination.

Self-checkout could be one factor

Hartmann points out that the job figures in their analysis include everyone on the payroll, including part-time employees. Women who also care for families often take part-time work because of the flexibility it allows. She suspects jobs such as cashier may be disappearing, too, as stores open more self-checkout registers.

The IWPR still has more analysis to do to determine why this gender gap in job losses is appearing and which groups are most affected, but Hartmann nonetheless sees what they’ve found so far to be worrying. “Women deserve a share of these better jobs,” she says. They do, after all, still control most of the household spending in the US.