Update: It turns out that Google launched a Panda refresh a few days ago, and Matt Cutts says this is more likely the culprit for Searchmetrics’ lists.

Danny Sullivan has Cutts’ comment:

There’s a pretty big flaw with this “winner/loser” data. Searchmetrics says that they’re comparing by looking at rankings from a week ago. We rolled out a Panda data refresh several days ago. Because of the one week window, the Searchmetrics data include not only drops because of the webspam algorithm update but also Panda-related drops. In fact, when our engineers looked at Searchmetrics’ list of 50 sites that dropped, we only saw 2-3 sites that were affected in any way by the webspam algorithm update. I wouldn’t take the Searchmetrics list as indicative of the sites that were affected by the webspam algorithm update.

Google is in the process of rolling out its Webspam update, which the company says will impact about 3.1% of queries in English.

Whenever Google announces major updates, Searchmetrics usually puts together some data about what it determines to be the top winners and losers from the update, in terms of search visibility. They’ve put out their first lists for this update.

“There could be other iterations from Google that we’re not aware of at the moment, but Searchmetrics is tracking closely and will update the list accordingly,” a Searchmetrics spokesperson tells WebProNews. “These are the first numbers and Searchmetrics will have more in the future, but we want to stress that the loser list could change in the next few days.”

“It’s unusual for Google to make major update on a Wednesday,” says Searchmetrics Founder Marcus Tober. “Normally Google makes this kind of updates on a Monday or Thursday. That’s why I assume that in the next days we’ll see more updates and this update is just the beginning. That’s why, all results in the winner and loser tables are marked as preview.”

“In a first study I took over 50.000 keywords from short-head to medium and low search volume and looked at the current rankings from position 1 to 100,” Tober adds. “So I analyzed 5,000,000 URLs and compared the rankings to last week. In my second study which is not finished yet I take one million keywords to get a complete overview, but this will take more time.”

Google did say yesterday, it was launching over the next few days.

Here’s Searchmetrics’ list of biggest losers:

Here’s their list of winners:

We’ll be taking a closer look at some of the sites on these lists.

See also:

Google Webspam Algorithm Update Draws Mixed Reviews From Users
Google Webspam Update: Where’s The Viagra?
Google Webspam Update: “Make Money Online” Query Yields Less Than Quality Result