A recent study examining 14,419 fiction ebooks primarily sold on Amazon found that 20% of titles contained more than 25% of text generated by AI. These AI-generated books accounted for 12.1% of sales and 11.3% of revenue during their initial release period. However, their increasing presence has raised concerns about how they might affect human authors. Between January 2023 and March 2026, the number of ebook titles in the study's sample increased by nearly 19 times, while unit sales and revenue grew by 7.3% and 8.9%, respectively. This suggests that the digital marketplace is expanding faster than readers can consume content, potentially reducing visibility and income for books written by humans, especially in genres where services like Kindle Unlimited play a major role. Amazon has stated that it has safeguards in place to prevent, detect, and remove content that violates its policies, regardless of whether it was created by AI. The company’s Kindle Direct Publishing service requires users to report AI-generated content, although AI used for editing, improving, or generating ideas is considered "assistance" and does not need to be disclosed. The study found that none of the books analyzed openly claimed to use AI, and the researchers had no access to internal communications with Amazon about the issue. Barnes & Noble has taken a cautious approach, with its CEO stating the company is actively excluding AI-generated books from its online catalog and not knowingly ordering them for its stores. However, the company has not imposed an absolute ban, citing the difficulty in clearly defining what constitutes AI-generated content. The study also highlights copyright concerns, referencing the fourth factor of American fair use, which considers the effect of a use on the current or potential market of a protected work. The Copyright Office notes that courts may weigh the impact of AI-generated content on sales and the potential harm from widespread use of such content. In China, Huaxia Publishing House has started including warnings in certain books stating that their content cannot be used to train artificial intelligence, though enforcing this is technically challenging. Meanwhile, in Japan, the National Library of the Diet is developing a lightweight OCR tool to convert images of old books into text without requiring high-powered computers. Other developments include a campaign by young British authors against the unauthorized use of their works by generative AI, and the launch of Bookpact.ai by Dutch publishers to regulate how AI companies use books. In Australia, 17 organizations have urged the government not to reopen copyright in favor of AI companies, stressing the need for negotiated licenses. The use of AI in the book industry is growing, with applications ranging from audiobook production to self-publishing platforms and e-reader enhancements. However, concerns about copyright, transparency, and the quality of AI-generated content remain significant.