The European Commission has published a study conducted by Spark Legal Network and the University of Queen Mary concerning the review of the Merger Regulation regarding minority shareholdings.
The study involved the assessment of the features of a certain number of national merger control regimes, which provide for the control of minority shareholdings´ acquisitions; and research on rights attached to different levels of minority shareholdings. On the basis of the data collected, the study analyses the modalities of merger control of minority acquisitions in the various jurisdictions, in order to present important considerations which any EU regime being designed should consider. Finally, the study considers whether it is possible to define a level below which shareholding might be generally considered to be passive.
You can find further information here.