Two directors stepped down from Nextdoor Holdings Inc. after the US Justice Department raised concerns that they were also serving on the board of rival social media company Pinterest Inc. in violation of antitrust laws.

“We remain steadfast in our commitment to protect competition by preventing interlocking directorates that we believe violate Section 8 of the Clayton Act,” said Deputy Assistant Attorney General Andrew Forman said Wednesday in a statement.

Nextdoor operates social networks serving neighborhood communities, while Pinterest offers pinboards to help users style events and decorations among other items.

The department has been cracking down on simultaneous directorships involving competing companies, which has led to resignations at 11 companies.

Leslie Kilgore and Andrea Wishom stepped down from the board of Nextdoor as of Aug. 1, the company said in a securities filing.

A former marketing executive at Amazon.com Inc. and Procter & Gamble Co., Kilgore also serves on the boards of Netflix Inc. and closely held communications platform Discord Inc.

Wishom is the president of privately held management company Skywalker Holdings LLC and a former executive at Oprah Winfrey’s studio Harpo Productions Inc. She also serves on the board of Tory Burch.