>And I disagree with the “within a billion or two,” though do think within a few tens of billions is accurate.
It is clear from the statement that we are almost entirely talking about 30 year MBS purchased in 2021.
3% 30yr MBS were about $105 throughout 2021. These were about $89.2 at the end of 2022 (10-k filing), and about $89.4 today.
You might say, "but they may have put it 30yr MBS!". The thing is, you can validate this by the ammount they lost from 2021 to 2022. It also doesnt make much of a difference if they bought slightly different rate MBS at 2.5% or 3.5%, as they track pretty closely. Lastly, MBS value havent changed much since the time of the 10-k filing.
To get "a few tens of billions" difference, they would have had to tripple their losses on MBS in a time when MBS value has been stable.
https://fred.stlouisfed.org/series/MORTGAGE30US
https://www.mortgagenewsdaily.com/mbs/umbs/30/30