Amazon says that, for the first time, it's now selling more Kindle books than print books.
The company started selling Kindle books in November 2007. It took nearly three years for Kindle book sales to overtake hardcover book sales, but by January this year they'd beaten paperbacks.
Now, though, even hardcover and paperback sales combined are no match for Kindle sales.
"Customers are now choosing Kindle books more often than print books. We had high hopes that this would happen eventually, but we never imagined it would happen this quickly - we've been selling print books for 15 years and Kindle books for less than four years," says Amazon CEO Jeff Bezos.
Since April 1, for every 100 print books Amazon.com has sold, it's shifted 105 Kindle books - and bear in mind that many print books aren't available in a Kindle edition. Further, this figure doesn't include free Kindle books, and would presumably be considerably higher if they, too, were counted.
Kindle books are now outselling hardbacks by more than two to one, even as hardback sales grow.
The company says it's sold three times as many Kindle books so far this year as it did in the same period last year. It's given the company's US books business its fastest year-over-year growth rate, in both units and dollars, in over ten years.
Part of the reason is the way e-readers have fallen in cost; the company recently slashed the price of the Kindle with the launch of Kindle with Special Offers for $114.