ATON (Account Transfer Online Notification) - is an electronic transfer method that eliminates the physical exchange of paper documentation between brokerage institutions in Canada (signed documents are still required to begin the process).
ACATS (Automated Customer Account Transfer Service) - is an almost entirely electronic system that executes the transfer of financial securities from a trading account at one institution to the trading account at another in the United States.
Do these systems have some sort of interoperability that allows them to perform cross-border transfers? How do cross-border securities transfers between the USA and Canada usually happen? Does anyone have any insight into this process and what happens under the hood?