Windows Phone 8.1 supports installation of Apps and Games to the SD card, but just as we posted earlier, developers will have the choice to whether allow the installation to the SD card or not. When I updated to Windows Phone 8.1, I was able to move all of the apps (except system apps) and games to the SD card.
But today WhatsApp has decided to not allow the installation of app on the SD card. You cannot update to the next beta version unless you move the app back to the phone memory. However, the public version is not yet updated and can still be moved to the SD Card.