This study presents estimates of the global expenditure on article processing charges (APCs) paid to six publishers for open access between 2019 and 2023. APCs are fees charged for publishing in some fully open access journals (gold) and in subscription journals to make individual articles open access (hybrid). There is currently no way to systematically track institutional, national or global expenses for open access publishing due to a lack of transparency in APC prices, what articles they are paid for, or who pays them. We therefore curated and used an open dataset of annual APC list prices from Elsevier, Frontiers, MDPI, PLOS, Springer Nature, and Wiley in combination with the number of open access articles from these publishers indexed by OpenAlex to estimate that, globally, a total of \$8.349 billion (\$8.968 billion in 2023 US dollars) were spent on APCs between 2019 and 2023. We estimate that in 2023 MDPI (\$681.6 million), Elsevier (\$582.8 million) and Springer Nature (\$546.6) generated the most revenue with APCs. After adjusting for inflation, we also show that annual spending almost tripled from \$910.3 million in 2019 to \$2.538 billion in 2023, that hybrid exceed gold fees, and that the median APCs paid are higher than the median listed fees for both gold and hybrid. Our approach addresses major limitations in previous efforts to estimate APCs paid and offers much needed insight into an otherwise opaque aspect of the business of scholarly publishing. We call upon publishers to be more transparent about OA fees.

翻译：本研究估算了2019年至2023年间全球为开放获取向六家出版商支付的论文处理费（APC）支出总额。APC是在部分完全开放获取期刊（金色模式）以及订阅期刊中为单篇论文提供开放获取（混合模式）所收取的出版费用。由于APC定价、付费文章对象及支付方信息缺乏透明度，目前尚无系统追踪机构、国家或全球开放获取出版支出的有效途径。为此，我们整理并使用了来自Elsevier、Frontiers、MDPI、PLOS、Springer Nature和Wiley的年度APC公开标价数据集，结合OpenAlex收录的这些出版商的开放获取文章数量进行估算。结果显示，2019年至2023年间全球APC总支出约为83.49亿美元（按2023年美元计值为89.68亿美元）。我们估算2023年APC收入最高的出版商依次为MDPI（6.816亿美元）、Elsevier（5.828亿美元）和Springer Nature（5.466亿美元）。经通胀调整后，年度支出从2019年的9.103亿美元增长至2023年的25.38亿美元，增幅近三倍；混合模式费用持续高于金色模式，且实际支付APC中位数均高于两类模式的标价中位数。本研究方法突破了既往APC估算的主要局限，为学术出版行业中这一长期不透明的领域提供了关键洞察。我们呼吁出版商提高开放获取费用的透明度。