This paper provides the first estimates of the extent of common ownership of competing firms in Australia. Combining data on market shares and substantial shareholdings, we calculate the impact of common ownership on effective market concentration. Among firms where we can identify at least one owner, 31 per cent share a substantial owner with a rival company. Analysing 443 industries, we identify 49 that exhibit common ownership, including commercial banking, explosives manufacturing, fuel retailing, insurance and iron ore mining. Across the Australian economy, common ownership increases effective market concentration by 21 per cent. Our estimates imply that if listed firms seek to maximise the value of their investors’ portfolios, then they place the same value on $3.70 of their competitors’ profits as on $1 of their own profits. We discuss the limitations of the available data, and the potential implications of common ownership for competition in Australia.

中文翻译：

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竞争公司的共同所有权：来自澳大利亚的证据

本文提供了对澳大利亚竞争公司共同所有权范围的初步估计。结合市场份额和大量持股的数据，我们计算了共同所有权对有效市场集中度的影响。在我们可以确定至少一个所有者的公司中，31% 的公司与竞争对手公司共享一个主要所有者。通过分析 443 个行业，我们确定了 49 个具有共同所有权的行业，包括商业银行、炸药制造、燃料零售、保险和铁矿石开采。在整个澳大利亚经济中，共同所有权将有效市场集中度提高了 21%。我们的估计意味着，如果上市公司寻求最大化其投资者投资组合的价值，那么他们将竞争对手的 3.70 美元利润与 1 美元自己的利润相同。