Merging Nurbs Vertices

Hi there,

I’m trying to learn a bit about nurbs surfaces. I created several nurbs circles, connected them with ‘F’ and was wondering if there is a way to close the last two circles. When editing polys you simply merge them with ALT+M - can’t this be done when editing nurbs?

I tried converting the object into a mesh, merged the vertices but then can’t get back to curves mode.

Any help is greatly appreciated!