United Airlines said it expects to lose money over the 737 Max 9 grounding, the first indication of the financial impact of the door plug blowout saga

• United Airlines is the world's biggest operator of the Boeing 737 Max 9.
• A Monday filing said it expects to lose up to 85 cents per share in Q1.
• It also saw its busiest-ever travel period in the last two weeks of December.

United Airlines said it expects to lose money as a result of the Boeing 737 Max 9 grounding, in a Monday filing.

It forecast an adjusted loss of between 35 and 85 cents per share for the first quarter of this year.

And it estimated its cost per available seat mile, excluding fuel costs, will rise three percentage points due to the grounding — reducing the airline's efficiency.