This thesis examines the effect of U.S. and European news announcements on the spread between Greek and German bonds as well as to the yield to maturity of Greek and to the yield to maturity of German bonds. It calculates the spreads as the difference between these two yields to maturities. It is important to focus on the fact that the announcements are divided in scheduled in which the timing is known from the beginning but not the content and in the unscheduled in which neither the timing nor the content is known.