8.IV Performing calculations and operating databases

The final piece of the MiFID I equity post-trade transparency regime was the operational part. The MiFID I equity post-trade transparency regime implied a greater operational quality compared to the ISD. The introduction of a harmonised regime for deferral of equity post-trade data publication, meant more calculations and estimates, as well as the publication of the results. As examined above, MiFID I permitted deferral of post-trade data publication for ‘large in scale’ transactions (in relation to client orders). The length of deferral depended on the average daily turnover of the share and the size of the transaction.1 Without regulatory support, market participants would have difficulty in seeing what the average daily turnover of a share would be (the size of the transaction would be clear). In other words, market participants would struggle in seeing whether and, if so, which length of deferral applied. A lack of regulatory support would not only impose a burden on the market participants in having to calculate large in scale transactions themselves, it would also risk different approaches across the EU. The EU did not take such consequences for granted. Similar to the MiFID I equity pre-trade transparency regime,2 NCAs were subject to (1) harmonised provisions for calculations and estimates and (2) CESR operated EU databases. As a result, MiFID I embodied the first steps towards an EU approach for equity post-trade transparency calculations/estimates and databases.