MVC 5 ASP.NET Identity Single Sign On

I have three web applications in my dmz.  A login app and two other web applications that use forms authentication.  They all work together. By simply sharing a machine key and a few configuration settings I was able to easily implement SSO (Single Sign On) with windows forms authentication.  I have found very little documentation on SSO and the new ASP.NET Identity framework (owin).  I guess I could just put a login controller in all my apps but the problem is the authentication ticket doesn't seem to be shared.  Even if I use the same machine key.  Anyone know of any resources available for doing this?  Any help would be greatly appreciated.