The public does know the current value of all securities, and of several different buckets. Yes, these market values will change at different rates for individual assets, and we dont have a list of every stock, bond, and loan.

We still have a very good understanding of the "delta" and the magnitude of the loss, if not with crystal clarity.

Nearly all of the unrealized loss was in securities more than >10 years. They had 15.1 billion in unrealized HTM losses. 14.7 billion of this had a maturity >30

9 billion is agency MBS

2 billion in agency collateralized mortgage obligations

2.3 billion in commercial mortgage backed securities, and

1.2 in municipal bonds and notes.

They actually have relatively few treasuries, and none in their HTM portfolio. Unrealized losses on treasuries are ~1 billion, And mostly treasuries from treasuries less than 12 months ( contrary to what most people report).

I really recommend actually looking at their filing. It is extremely detailed.

https://d18rn0p25nwr6d.cloudfront.net/CIK-0000719739/f36fc4d...