You are dealing with wire-transfers here. So there isn't really a way to undo a wire transfer. The recipient would need to voluntarily create another wire transfer back to you of the same amount.
So an interface like this only controls the money on Citi's end. Once the wire transfer occurs, there wouldn't be any way for this software to undo that transaction.
You could create a psuedo-undo in this software tool, which is how Gmail creates an "undo send" feature. Like a wire-transfer, once you send an email, there is no way to undo it. The email is sent to the recipients servers, there is no way to reverse that. Gmail creates a Psuedo-undo which means that they basically wait after you click "send" and they don't send the email right away. They wait 30 seconds or so before actually sending the email. So if you click "undo" during that artificial waiting period, then it simply cancels the send that hasn't occured yet. It feels like "undo" to the sender, but in reality an artificial waiting period was created, which allows you time to cancel it before sending. Not a proper "undo", but it acts similarly. But it is worth noting that once that artificial waiting period is up and the email is actually sent, then there is no undo anymore.
In the case of this story, you could potentially create a psuedo-undo. The software could create an artificial waiting period before initiating the wire transfer, which would allow time to undo. But the problem is that no one would have noticed it until the wire transfer was completed anyway. Someone noticed that $900M left the account when they thought money was staying in the bank. Only then did they realize that the mistake was made. Three people signed off on this transaction before it was sent and all three thought it was correct. So a psuedo-undo wouldn't have helped in this case.
So an interface like this only controls the money on Citi's end. Once the wire transfer occurs, there wouldn't be any way for this software to undo that transaction.
You could create a psuedo-undo in this software tool, which is how Gmail creates an "undo send" feature. Like a wire-transfer, once you send an email, there is no way to undo it. The email is sent to the recipients servers, there is no way to reverse that. Gmail creates a Psuedo-undo which means that they basically wait after you click "send" and they don't send the email right away. They wait 30 seconds or so before actually sending the email. So if you click "undo" during that artificial waiting period, then it simply cancels the send that hasn't occured yet. It feels like "undo" to the sender, but in reality an artificial waiting period was created, which allows you time to cancel it before sending. Not a proper "undo", but it acts similarly. But it is worth noting that once that artificial waiting period is up and the email is actually sent, then there is no undo anymore.
In the case of this story, you could potentially create a psuedo-undo. The software could create an artificial waiting period before initiating the wire transfer, which would allow time to undo. But the problem is that no one would have noticed it until the wire transfer was completed anyway. Someone noticed that $900M left the account when they thought money was staying in the bank. Only then did they realize that the mistake was made. Three people signed off on this transaction before it was sent and all three thought it was correct. So a psuedo-undo wouldn't have helped in this case.