I'm wondering if someone else can make the same correlation we have. Around 10/1, Google added features to its Show Options panel, notably "Fewer shopping sites" and "More shopping sites". We rank very well in a competitive US vertical, and our breadwinning keyword has been #1 for years (except a brief period when we were knocked to #2 by a combination of bowling attempts and a link-buying competitor). Until this month, we've always had 8+ stacked sitelinks in our listing, but now we only have 3 horizontal. This appears to coincide with Google's Search Options update. The clues are:
1) Timing
2) When "More shopping sites" is clicked, we get the stacked sitelinks back
Has anyone else noticed a similar loss that appears to be a result of the Search Options update?