This thesis contains a number of in-depth studies of the two largest sovereign bond markets in the world - The U.S. Treasury market and the European sovereign bond market. It examines aspects of the development of these important markets over recent decades when fundamental technological changes are prevalent. There is heightened competition between different trading platforms and regulators seek more transparency. While technology improves many aspects of liquidity and transparency, it also increases network externalities that have some negative consequences during the 2007-2009 financial crisis and the subsequent sovereign debt crisis in Europe. The thesis also makes use of the high quality data from these markets to shed light on crisis event.