It has been reported today that Horizon Zero Dawn has "sold" more than 3.4 million copies as of April 30. That is a period of roughly two months since the game's release. Now, I say "sale" because it has not been specified if those units were sold through to consumers or simply sold to retail outlets, though Sony has only revealed sold-through figures on recent reports.

It was however specified that at least 915,000 of that 3.4 million figure were digital sales directly to consumers. Shawn Layden briefly touched upon the success of the digital store in statements issued earlier today.
"We thought people would go for the digital store because they didn't want to get off the sofa, get in their car, and go drive and get it. We underestimated that.

"People will get the digital copy because they don't want to get off the sofa and put a disc in the machine."

Prior to this updated figure, the last official numbers said that the game sold 2.6 million copies in its first two weeks.