Authors: Kimmo Soramäki, Morten L. Bech, Jeffrey Arnold, Robert J. Glass, and Walter E. Beyeler

We explore the network topology of the interbank payments transferred between commercial banks over the Fedwire^® Funds Service. We find that the network is compact despite low connectivity. The network includes a tightly connected core of money-center banks to which all other banks connect. The degree distribution is scale-free over a substantial range. We find that the properties of the network changed considerably in the immediate aftermath of the attacks of September 11, 2001.