We analyse deviations between interest rates paid in the Swiss franc unsecured money market and the respective Libor rate. First, banks that have access to the secured interbank market and the SNB's monetary policy operations pay less than banks without access. Second, domestically unchartered, foreign banks pay more than domestic banks. We find that these segmentations are limited both during normal times and during the financial crisis starting 2007 thanks to open access to the secured interbank market and the SNB's monetary policy operations. These findings reveal that a neglected aspect of monetary policy implementation matters, namely access policy.