Update 02/10/23: The BTT upgrade is complete. Wallets are enabled.
Bittrex will support the BitTorrent upgrade and ticker change of BTTOLD (TRC-10) to BTT (TRC-20). The BTTOLD wallet will be disabled on 27 January 2023, in preparation for the upgrade and ticker change.
Token holders' exchange balance totals will reflect the same total that they had prior to the upgrade in a 1:1000 manner. Once the upgrade and ticker change are complete, the old BTTOLD (TRC-10) tokens will no longer be supported on Bittrex. Once the upgrade is deemed satisfactory, Bittrex will enable the BTT wallet.
For more information:
https://medium.com/@BitTorrent/launch-of-bttc-mainnet-and-btt-redenomination-plan-2eacfe26d22