Private equity investor Graphite Capital announced on Wednesday that it has sold its investment in Wonderbly, a publisher of premium personalised books, to Penguin Random House.

Wonderbly, founded in 2013, has sold over 11 million personalised books across 140 countries and was shortlisted for both Children's Publisher of the Year and Publisher of the Year at the 2025 British Book Awards.

Under Graphite Capital's ownership since July 2021, Wonderbly more than doubled its revenue and EBITDA, driven by organic growth, product innovation and marketing of its existing catalogue. The company expanded its offering with new book formats and invested in data science, marketing personalisation and pricing strategies, improving scalability and profitability.

Strategic bolt-on acquisitions included the Book of Everyone in 2022 and Historic Newspapers in 2023, which strengthened Wonderbly's partnerships with UK and US newspaper groups.

After starting as a children's publisher, Wonderbly has diversified into adult books, now accounting for 25% of sales, and embraced AI to enhance development, automation and customer experience.

Wonderbly also earned B Corp certification in March 2024, highlighting its environmental and social responsibility.