There were seven preorder books on Amazon's top 100 as of the morning of July 16, a higher number than normal for the bestselling chart. The top preorder is also the preorder with one of the latest publication dates: Rick Riordan's The Mark of Athena doesn't come out until October 2, but it's already #20 on Amazon's bestseller list. A similar pre-publication buzz happened with Riordan's last book, The Serpent's Shadow, which published this past May and is still selling well, currently at #50 on the bestseller list.
Immediately behind The Mark of Athena is Daniel Silva's The Fallen Angel, landing at #21. The other preorders are Reflected in You by Sylvia Day (#48, October), Forks Over Knives:The Cookbook (#59, August), Creole Belle by James Lee Burke (July 17), Where We Belong by Emily Griffin (#88, July 22), The Third Wheel (Diary of a Wimpy Kid,Book 7) by Jeff Kinney (#94, November), and Broken Harbor by Tana French (#99, July 24). Only Sylvia Day's novel (#75) and Silva's novel (#69) are in the Kindle top 100.