Here are some statistics from the worldwide eBook market:
According to most reports, Amazon accounts for 65% of the US eBook market. However, that figure does not take into account indie books published without ISBN. When you add indie books, Amazon’s market share rises to a whopping 74%.
Almost the entirety of the remaining 26% belongs to the other four major online retailers. They are the Apple iBookstore, The Nook Store, Kobo Bookstore and Google Play Books. With Amazon’s dominance in the eBook reader market, it is unlikely we will see much change for these four players.
Self-published indie books account for a quarter of all sales of the non-Amazon retailers and almost a third of their profits. Also, about a quarter of those books do not have the International Standard Book Numbers (ISBN).
If you look at the eBook market in the US as a whole, 33% of all books sold have no ISBN. Most indie authors only sell eBooks and don’t get the ISBN unless there is a print-run expected. Self-published authors sell to a dedicated fan base, often in volumes that don’t justify print-runs.
Across the entire US ebook market, ebooks without ISBNs now command a greater share of consumer ebook purchases, reading time, and author earnings than all of the AAP’s 1,200 publishers put together, including the Big Five.
It is clear from the above that indie books command a larger part of the eBook market, with the likelihood of that increasing going forward.