There's the DCI 4K which has a resolution of 4096 × 2160. There are two standards for 4K out there.
If you're a graphic designer, I've some tips for you too. My perspective will be from someone who's going to use the monitor mainly for video editing purposes. I'm a graphic artist at a newspaper company, and on the side I run this blog and a Youtube channel.
Let me start with some background on the work I do.
This article looks at things you should know before getting a 4K monitor, and also looks at selected models in the market currently.