Sigma levels measure the accuracy, quality, and timeliness of various processes, including underwriting, redemptions, dividend and interest payments and reorganization announcements. We look at three different sigma levels: Internal sigma levels to measure the impact of defects that are identified as originating within DTCC, External sigma levels to see the impact of defects identified as originating outside DTCC, and Overall sigma levels to measure the performance of the process in general, without distinguishing between the sources of the defects.