To answer your question the links are evenly distributed, not only to the us sites, but the other European sites as well.

They are all selling the same industry products, although the site I'm talking about sells everything, the others are a smaller subset.

In other words, if we use pet products as an example, the main site in question sells all, dog, cat, hamster, bird, etc.  Another of the US sites sells the same animal group products, but just less product offering.  The other US sites sell only specific animal products, so one is dog only, another one cat, etc.  The other European sites again sell other animal groups, but a smaller product offering again.

And we have found that the links were followed before, the subsequently made them no follow after the loss.  All US sites are currently down in traffic over last year now.

Still waiting to look at the analytics for the timeframe, but we do know that the top keyword dropped on or about April 23, 2012 from the #1 ranking in Google - something they had held for years, and traffic dropped over 15% that month and further slips since.

Just looked at Google Webmaster Tools and see over 2.3MM backlinks from "sister" compainies from their footers.  One has over 700,000, the rest about 50,000 on average and all going to the home page, and all using the same anchor text, which is both a branded keyword, as well as a generic keyword, the same one they ranked #1 for. They are all "nofollows" but we are trying to confirm if the nofollow was before or after they got hit, but regardless, Google has found them.

To also add, most of sites are from their international sites, so .de, .pl, .es, .nl and other Eurpean country extensions.

Of course based on this, I would assume the footer links and timing, was result of the Penguin update and spam.

The one issue, is that the other US "sister" companies listed in the same footer, did not see a drop, in fact some had increase traffic.  And one of them has the same issue with the brand name, where it is both a brand name and a generic keyword.  The only note that I will make about any of the other domains is that they do not drive the traffic this one used to. There is at least a 100,000+ visitor difference among the main site, and this additional sister sites also listed in the footer.

I think I'm on the right track with the footer links, even though the other sites that have the same footer links do not seem to be suffering as much, but wanted to see if anyone else had a different opinion or theory.

Thanks!
Jen Davis