Ummm. They announced over six months ago that the portfolio function was going away and major updates were coming....
You're lucky they kept it working as long as it did, to give you an opportunity to find new sources of the data you need.
There is no such link on the new Google finance front page, which is just a tab on the normal Google search page:
You must be using an old link that has now gone away, or is in the midst of going away.