  The ongoing controversy surrounding transformative agreements, which aim to
transition journal publishing to full open access, highlight the need for
large-scale studies assessing the impact of these agreements on hybrid open
access. By combining publicly available data from various sources, including
cOAlition S Journal Checker, Crossref, and OpenAlex, this study presents a
novel approach that analyses over 700 agreements. Results suggest a strong
growth in open access between 2018 and 2022 from 4.3% to 15%. During this
period, 11,189 hybrid journals provided open access to 742,369 out of 8,146,958
articles, representing a five-year open access proportion of 9.1%. Authors who
could make use of transformative agreements at the time of publication
contributed 328,957 open access articles. In 2022, 143,615 out of 249,511 open
access articles in hybrid journals or 58% were enabled by transformative
agreements. This trend was largely driven by the three commercial publishers
Elsevier, Springer Nature, and Wiley, but the open access uptake varied
substantially across journals, publishers, disciplines, and country
affiliations. In particular, the OECD and BRICS areas revealed different
publication trends. In conclusion, this study suggests that current levels of
implementation of transformative agreements is insufficient to bring about a
large-scale transition to full open access.
