Steve Bohme, research director at Nielsen Book UK, said self-published titles rose from 16% of the e-book market to over a fifth in 2015.
Overall growth in e-book sales slowed, up by just 5%, in stark contrast to previous years.
Bohme said: “All of the e-book growth in 2015 can be attributed to a rise in purchasing of Amazon/self published titles, with purchases of e-books from mainstream publishers down slightly on 2014.”
Bigger publishing houses struggled with digital sales following agreements with retail giants like Amazon allowing them, not the seller, to set prices. Customers have turned away from high cost digital editions.
Bohme added that because self-published titles are “still around half the price of e-books from mainstream publishers”, the overall price paid for e-books fell by 1% in 2015. In contrast, the average price paid for print books rose by 2%. It meant that by value e-book share of the overall book market fell back to 16% in 2015.
Purchases of audiobooks rose markedly last year by 27%, accounting for 3% of overall sales.
Print “gained ground” over e-books in several genres last year – general fiction, biography, cookery, reference, sport, science and YA – and remained dominant in highly illustrated sections such as arts, crafts and younger children’s books. Digital, meanwhile, continued to make more gains in the romance, crime, science fiction, self-help and fitness & business/IT areas.
Older and middle-aged women continued to move their book purchasing to digital in 2015, but lighter fiction buyers shifted back towards print in 2015.