It's believed by whom?
I think AOL Time Warner still has the record at over $50 billion, unless you're talking about some specific form of impairment.
CNBC
In addition to the AOL mentioned elsewhere -
1. GE took a $22B impairment in 2018.
2. Shell took a $22B write down in 2020.
3. ConocoPhillips incurred a $34B impairment in 2009.
It's such an absurd number that I strongly suspect Ford is taking this opportunity to play some accounting games.
If it is a real number, then I am darkly amused at how much money they could lose and still only make three EVs.
It is believed that this is the largest impairment ever from a company.