As of March 31, this year, they held 53,794 bitcoins. For comparison #MSTR is reported to have 152,800.

MSTR reference:

https://www.forbes.com/sites/emilymason/2023/08/01/microstrategy-adds-to-its-bitcoin-stash-in-q2-crypto-aids-results/?sh=4bad414f16b9

Your Tether asset list is not the same as this one:

https://assets.ctfassets.net/vyse88cgwfbl/24G4DuQ0HE7h7EQE6vGy4J/8a8a170edf687ea07b3f86048af8b87b/ESO.03.01_Std_ISAE_3000R_Opinion_31-03-2023_BDO_Tether_CRR.pdf