The liberal watchdog group Citizens for Responsibility and Ethics in Washington (CREW) on Thursday filed a complaint against senior White House adviser Jared Kushner, who is President Donald Trump’s son-in-law, for not disclosing his ownership interest in a real estate startup.

CREW asked the Office of Government Ethics to investigate Kushner’s failure to disclose “his ownership interest in an online real estate investment company called Cadre” in his public financial disclosure.

“He likely failed to disclose his ownership interest in documents connected with his request for a certificate of divestiture, meaning OGE apparently had incomplete information when it granted Kushner permission to sell similar assets and avoid paying certain taxes on them,” the watchdog group said in a release. “These cannot be written off as minor oversights, as Cadre reportedly has a value of $800 million.”

CREW executive director Noah Bookbinder said Kushner’s ownership interest was “not something he could easily overlook.”

“Kushner’s failure to disclose his ownership in Cadre is very troubling,” Bookbinder said. “OGE should investigate immediately and determine whether any sanction or referral is appropriate for Kushner’s potential disclosure violations and whether it is necessary for him to fully divest from Cadre.”

The Wall Street Journal in May reported, citing securities filings and unnamed sources familiar with with the matter, that Kushner cofounded and partly owns Cadre but failed to list it among his interests on his public disclosure form.

Billionaires George Soros and Peter Thiel, and Goldman Sachs, also have “stakes in the company,” according to the Wall Street Journal’s report.