Two women who lost their jobs at Twitter after Elon Musk took over are suing the company, claiming recent lay-offs disproportionately affected female employees.
About half the social media network’s workforce were let go early last month after Mr Musk bought the company for $44bn.
He subsequently told those remaining that they would need to work at “high intensity”.
“Going forward, to build a breakthrough Twitter 2.0 and succeed in an increasingly competitive world, we will need to be extremely hardcore,” he said in a message.
“This will mean long hours at high intensity. Only exceptional performance will constitute a passing grade.”
The lawsuit alleges that those requirements disproportionately affected women “who are more often caregivers for children and other family members, and thus not able to comply with such demands”.
The suit, filed for former employees Carolina Bernal Strifling and Willow Wren Turkal, claims 57% of female employees were laid off on 4 November, compared to 47% of male employees, citing a spreadsheet.
For women in engineering-related roles the gap is alleged to have been even greater, with 63% laid off, compared with 48% of men.
The suit has been filed by prominent workers’ rights attorney Shannon Liss-Riordan.
“The mass termination of employees at Twitter has impacted female employees to a much greater extent than male employees – and to a highly statistically significant degree,” Ms Liss-Riordan wrote.
Speaking outside a federal court in San Francisco, Ms Liss-Riordan said she wanted to show that the “richest man in the world is not above the law”.
She added: “We are arguing that the arbitration agreements (signed by…