According to the Journal, Plank turned to Ruhle for business advice, and she flew on the company's private jet. In some cases, her advice overruled that of other employees, sources told the newspaper.
The board reportedly stepped in at one point after emails were uncovered indicating that the duo may have been having a more intimate relationship.
Under Armour and Stephanie Ruhle did not immediately respond to Business Insider's request for comment. MSNBC declined to comment.
The board reportedly asked Plank about the nature of their relationship and whether he was using company assets. Plank told directors that no company funds were spent, the Journal wrote.But sources said that Ruhle would often fly on the company's private jet, which costs over $160,000 a month to lease.
"Ms. Ruhle flew with Mr. Plank and Under Armour staff to or from Cannes, Amsterdam and Austin, Texas. On trips from Cannes in 2015 and 2016, the plane stopped in Teterboro, N.J., and dropped off Ms. Ruhle, according to these people and flight records," the Journal wrote.
A spokesperson for Under Armour told the Journal that other executives also disembarked at this location and that it is common for Plank to bring family and friends on business trips, as there is no extra cost for additional passengers.
Read the Journals full report
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