Sauber team principal Monisha Kaltenborn is believed to have left her role following a disagreement with majority shareholders Longbow Finance, Motorsport Week understands.
Kaltenborn took up the role of team boss in 2012, becoming the first ever female Formula 1 team principal when she replaced team founder Peter Sauber, when he chose to scale back his responsibilities.
As part of that deal, Kaltenborn took an ownership stake in the Swiss outfit.
However with Sauber hitting financial troubles last year, a rescue deal was put in place by Longbow Finance which saw Kaltenborn relinquish her shareholding in the team, but she remained in charge.
It's believed a disagreement between the two parties has led to the 46-year-old stepping down from her role, though Sauber have yet to confirm this, nor have they responded to Motorsport Week's request for comment on the matter.