Recently, I started checking out the Percy Jackson film adaptions but I just ran across some articles where Logan Lerman who plays the film's main protagonist, Percy Jackson, in which he says that a third film is officially dead.
http://www.mtv.com/news/articles/172...n-lerman.jhtml
http://www.hypable.com/2014/03/26/lo...-be-happening/
While it's hard to fathom that an actor would be aware of what studio executives are planning, considering that both films made over $200m each, they weren't exactly failures. 20th Century Fox hasn't exactly made their plans known about the series but that Lerman has stated that he has no desire to continue on with future films.
The Percy Jackson series has generated 110 books in the series and nobody from the studio has said whether they are moving forward with a sequel or not.