AbstractThis article focusses on the non-coordinated effects of minority shareholdings in oligopolistic markets. It is demonstrated that minority shareholdings even when they fall below the usual thresholds can lead to a significant impediment of effective competition (SIEC) on a purely non-coordinated basis. This is particularly likely in a market with differentiated products, when a firm partially acquires shareholdings in its closest competitor and when the next best alternative products are only weak substitutes.