16.I Introduction

MiFID I abolished the ISD concentration-rule. The result was that MiFID I not only reduced the control of RMs over the market in trading services, but also over the market in the data generated from those trades.1 Under MiFID I investment firms could trade on RMs, MTFs, but also ‘in-house’ through agency crossing or (systematic) internalisation. Furthermore, under MiFID I equity pre- and post-trade data could be published through a wide range of publication arrangements, namely the arrangements of (1) RMs and MTFs and (2) third parties (data vendors), but also through (3) proprietary arrangements (e.g. the website of an SI).2 The result was that MiFID I permitted RMs, MTFs, investment firms trading outside such venues, as well as data vendors to generate market data revenues. MiFID I aimed to ensure ‘reasonable’ data prices by introducing the broad provision for all publication arrangements (e.g. RMs, MTFs, SIs, or third parties) to make the MiFID I equity pre- and post-trade data available at a ‘reasonable cost’.3 CESR complemented the MiFID I provision through formally non-binding guidance. The MiFID I framework and CESR guidance are examined below.