https://www.businessinsider.com/personal-finance/quantitativ...
Yes, about $8.8tn [1]. The Fed is running them off at about $60n a month [2]. (The Fed's optimal balance sheet is estimated to be around $4tn [3].)
The elephant in the room is the Fed's mortgages [4][5]. Those will have to start being sold soon, since rising rates mean mortgagers aren't refinancing and thus a run-off strategy doesn't reduce holdings.
[1] https://www.federalreserve.gov/monetarypolicy/bst_recenttren...
[2] https://www.federalreserve.gov/newsevents/pressreleases/mone...
[3] https://advisors.vanguard.com/insights/article/thefedsplanto...
[4] https://www.ft.com/content/1a2e829e-de82-4083-abcb-ceeb46a45...