Consultancy MDS Transmodal said the two companies will have just under half of the almost 176,700 TEU in feeder ship capacity deployed in Europe and the Mediterranean.
Strong demand for much of the year has kept North European ports under pressure, slowing attempts to ease the bottlenecks.
A more than 30% one-week drop in rates from Asia to the US West Coast is showing that the import rush sparked by the temporary pause in higher US tariffs will apparently be short-lived.