Fedwire Security Service - where securities are stored?

External question — Quantitative Finance Stack Exchange Author: Giorgi Lagidze Original post: https://quant.stackexchange.com/questions/85829 License: CC BY-SA 4.0 — https://creativecommons.org/licenses/by-sa/4.0/ Adaptation: HTML converted to plain text; contact email addresses removed. I’m trying to understand the technical architecture of the Fedwire Securities Service / National Book-Entry System (NBES). Federal Reserve documentation says that: A participant maintains a Securities Account with a particular Federal Reserve Bank. In 1998, the 12 Reserve Banks moved from 12 separate book-entry applications to a single NBES system. The Fed described NBES as using centralized computer processing, with all 12 Reserve Banks “linked to the same application” and “one electronic vault” for Treasury and agency book-entry securities records. Suppose Bank A has a Securities Account with the Federal Reserve Bank of New York containing $100 million par of Treasury CUSIP X. Technically, where is that $100 million position stored? Is the authoritative record something like: Central NBES / Fedwire Securities ledger Participant: Bank A Securities account: 123 CUSIP X: $100m par Maintaining Reserve Bank: New York with the New York Fed accessing/operating on that centralized record through some internal interface? Or does the New York Fed maintain its own separate electronic ledger/account database, with Fedwire Securities communicating with that system when a transfer is processed ? but how would that happen ? does each of 12 reserve banks run the fedwire security service software on their own ?