Concerns are mounting among publishers, booksellers and authors about the long-term impact of the 20p e-book price point used by Sony and matched by Amazon, with estimates suggesting that up to 15% of all e-books are now being sold for 20p.
However publishers with titles in the promotion have reported stronger than average growth in their e-book business.
The online retailers have offered dozens of e-books at 20p since July 2012, with the Kindle chart top 10 now dominated by 20p titles. There is now a growing feeling that the campaign has got out of hand, with some senior executives calling it a "disaster" for the book business.
President of the Publishers Association Ursula Mackenzie said: "Obviously I would support individual price promotions that boost an author's readership, but if we just go to rock bottom, it is not supportable. At the moment retailers take the hit, but if this becomes the price of e-books they won't continue to, and then it is authors who will suffer."
BA chief executive Tim Godfray commented: "The last thing we want to do as an industry at the moment is to undermine the perception that books generally are good value . . . How many of those in the supply chain will be able to cover their costs at this pricing level? This is not a recipe for helping to develop stronger bookshops."
Faber has seen several of its titles sold at 20p and its e-book sales grew 260% by value in 2012, well ahead of averages across the industry. Chief executive Stephen Page agreed with Mackenzie that "long term, 20p is not a price that expresses the true value of a copyright", but said that "short-term discounts are not new, and they exist in print and digital". He added: "Aggressive short-term pricing is one thing, but in the long term most e-books are priced sensibly. We think some very sensible pricing is emerging. There's a recognition that digital is different to physical, but people realise that doesn't always mean digital is lots cheaper‚ the intrinsic value is in the copyright."
Questions have been raised as to why publishers don't simply terminate their agreements with Sony, which is a marginal player in the e-book business. Asked if Faber would consider withdrawing its titles from sale with Sony, Page said he could not discuss arrangements with individual customers.
Canongate has also seen a huge boost to its e-book sales alongside the inclusion of selected titles for the 20p promotion, with the value of its e-book sales growing 240% in 2012 year on year. The publisher declined to comment for this article.
Author Nick Alexander said he was forced to price his self-published book The Half-Life of Hannah at 20p to get it into the Kindle top 10. "The top 10 is totally dominated by 20p e-books. With a couple of exceptions, the only chance to get there is to put a book at that price," he said. "It means I only get 10p for each book, when my books would usually be priced higher and I could receive more . . . I think it's a real noose around everyone's neck. I think everyone wishes it would disappear."
Sony and Amazon did not respond to requests for comment.