Yahoo has warned us of an up and coming Yahoo Search index update. Priyank Garg & Sharad Verma of Yahoo Search said Yahoo will “be rolling out some changes to our crawling, indexing and ranking algorithms over the next few days, but expect the update will be completed soon.”
The last Yahoo update was just about a month ago and Yahoo typically conducts updates monthly. I have not seen any discussion on fluctuations at Yahoo Search within the forums yet. Yahoo does explain we may see “some ranking changes and page shuffling in the index” during this update.