The Office of Government Ethics ordered Rice to divest from the company on July 9, according to filings first reported by The Daily Poster.
Although Biden has broadly taken action against oil pipelines, most notably canceling the Keystone XL oil pipeline, his administration has continued to allow the Line 3 project, which would bring Canadian oil through Minnesota to Wisconsin.
Environmental activists oppose the Line 3 project, but the cause has received far less national attention than other pipelines.
Last month, Biden administration officials indicated they would not withdraw permission for Line 3 in a major boon for the company.