Shipping has always had a special relationship with competition law and economics. Even if special competition law regimes for the shipping industry continue to exist, most countries nowadays accept the notion that shipping markets should be more competitive. Competition authorities monitor this in a more or less regular fashion, with various market concentration indexes. The liner shipping industry is peculiar in its widespread cooperation schemes between carriers, in the form of vessel sharing agreements, also known as consortia. Carriers engage in cooperation with all of their major competitors in a system of consortia that is highly interlinked. This brings considerable risks of abuse of market power. Yet, the system of inter-linked consortia has never been systematically mapped, nor do competition authorities appear to monitor them. This article addresses this gap, by proposing alternative indicators, in addition to the traditional industry concentration indexes such as the Herfindahl-Hirschman Index (HHI), that take the reality of consortia into account. Here, five possible alternative indicators are considered: the market share of consortia and independent operators; the share of consortia exceeding market share thresholds; the industry market concentration of consortia; a modified HHI that takes consortia into account; and interlinkages between consortia. We analyse the current state of concentration of liner shipping on the basis of these indicators using a new and unique database that contains deployed ship capacity of container carriers on all of their liner services. Based on this dataset we provide an overview of differences in industry concentration across world regions and developments over time. Traditional indicators show an increase in industry concentration. For example, over the trade corridors to and from Northern Europe, the HHI scores in 2006 ranged from 604 to 2463, and from 1164 to 4882 in 2021. The alternative criteria show additional industry concentration. We show that in 2021, 704 out of more than 1500 agreements among carrier consortia had a combined market share of at least 30%, and 102 of them had a combined market share of at least 50%. We also observe that in 2021, the carriers active in alliances operated 85% of the consortia capacity. Although carriers that are in the same alliance operate most of these consortia, it is also noteworthy that carriers that are not in the same alliance operate a considerable part (24%) of the consortia. Our calculations of modified Herfindahl-Hirschman Index (MHHI)indexes that take consortia into account show that industry concentration is higher when consortia are taken into account: for example on the trade corridor Northern Europe-North America East Coast, the MHHI has reached the threshold of 2500 points, despite an HHI score of around 1500. In the conclusion of the article, we put forward ways in which these alternative indicators could be used by competition authorities.
