"Every tether is backed by a reserve and their reserve is more than what is in circulation," said Gregory Pepin, Deltec Bank's deputy CEO.
Deltec Bank & Trust announced it had invested customer funds in bitcoin since the cryptocurrency's price was around $9,300.
Bitfinex says early Friday it repaid fully of the loan to Tether.
iFinex, the parent company of Bitfinex, has parted ways with its old offshore services provider for a new firm.
The wisp of a signature on Deltec Bank's letter to Tether is the least of it. More important is the language around liability.