Why did IBKR liquidate my stock when I had unrealized profit in my Commodities segment?

IBKR will not create a negative cash balance or increase an existing negative cash balance in your Commodities segment for the purpose of sweeping funds to cover a margin deficit in the Securities segment. It is possible that the Commodities segment of your IBKR Universal account has positive Excess Equity from the unrealized profit of an open Future/FOP position but also has a negative cash balance. In this example, if there was a margin deficit in the Securities segment then IBKR would begin to liquidate Securities positions as there is no positive unpledged cash available to be swept over from the Commodities segment.