(9)Trade repositories are relatively new entities that provide new regulated financial services and therefore a reliable measure of their turnover does not yet exist. Nonetheless, in order to estimate the trade repositories’ turnover, several indicators should be taken into account, in particular the trade repositories’ core financial revenues generated from centrally collecting and maintaining records of derivatives, excluding any revenues arising from ancillary services, the number of trades reported for a certain period and the number of trades outstanding at the end of each period. In the first year of operation of the trade repository, the supervisory fee should correspond to the supervisory effort carried out by ESMA for its supervision since the date of registration until the end of the year, on the basis of registration fees determined according to the expected total turnover level.