Study Finds Google’s Penguin Update Getting Stricter Over Time

disavow links penguinA study by Portent, an Internet marketing company, shows that Google’s tolerance of spammy links to trigger a Penguin algorithm ranking drop has declined by 30% since the Penguin algorithm launched.

The study shows that of the 500,000 links found, Google has been steadily reducing its tolerance for webspam. Now, Google is likely to penalize sites with as little as 50 percent suspicious links in their link profiles, whereas 80 percent was required when Penguin first launched.

Portent analyzed about 10,000 links pointing at each of the top 50 sites on the 2012 Inc. 5000 list. They then captured the SEOMOZ and Majestic SEO data for each incoming link. They designed a crawler to score the link as spam based on the page the link is linking to being related to the page the link is coming from. They did this and collected data on more than 250,000 links pointing at penalized sites, and 250,000 links pointing at non-penalized sites.

Here are the results over time:

Screen Shot 2013-03-19 at 2.26.52 PM

Of the top 50 websites on the Inc. 5000 list, the data showed:

  • 36 out of 50 — have “clean” profiles with less than 10 percent of their links coming from questionable sources.
  • A fifth of the sites are found with 11 to 39 percent of their links likely being spam.
  • Four websites are clearly at risk of being penalized with at least 40 percent of their links coming from suspicious pages.

The concern here is that Google is becoming less and less tolerant over spammy links in a site’s link profile. The question is, how low will this spam link tolerance go? 40%? 20%? 5%?

Related Topics: Channel: SEO | Link Building: General | Panda Update Must-Reads | Panda Update Tips


About The Author: is Search Engine Land's News Editor and owns RustyBrick, a NY based web consulting firm. He also runs Search Engine Roundtable, a popular search blog on very advanced SEM topics. Barry's personal blog is named Cartoon Barry and he can be followed on Twitter here. For more background information on Barry, see his full bio over here.

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  • Yakezie

    Id guess the level to go down to 10%. 10% is a good buffer just in case the spammy links weren’t built. Meanwhile, if you’ve truly got a great and growing site, any more than 10% shady backlinks won’t happen.

  • Henley Wing

    I thought this article was going to be about sites getting penalized because they were getting HUGE amounts of links in the beginning, then fewer and fewer as time went along

  • ArcticLlama

    Wow. This article is a good example of how structuring numbers in a sequence can lead to a specific conclusion. The way this one is written, Google is tightening the noose around websites with an increasingly smaller number of spammy links, from 80% to 50% and who knows how much lower it could go. This method gives the article an ominous, bad news tone.

    Here is the other way of looking at it. Previously, a mere 20% of your links had to be legit to avoid a Penguin penalty, suggesting that only the most spammy of all link profiles were even penalized. Now, you can still have up to half of your links be spammy and be just fine. So there is no need to worry for most legitimate sites unless you are the target of a negative SEO campaign. That would be good news. It’s interesting that this article chose to go with the bad news version.

  • Chase Anderson

    Where is their study?

  • Max Minzer

    @twitter-400766472:disqus, this is it, I believe:

  • Chase Anderson


  • Chase Anderson

    I’m finding the abrupt and rounded percentages to be very distracting. I can’t believe any amount of analysis was done if they produced a graph that looks so obviously faked.


    The thing is, I’m not really sure how “suspicious pages” are defined. Some people “threat” me to report my site to Google if I declined to remove their links on my site.

    I’m not sure my site is a suspicious page, having good DA ( 50+) and overall online reputation (91 percent according to WOT.)

    People are getting paranoid due to the algo updates, I suppose…

  • David Kimberley

    In an exercise to find out why my site was penalized I used some online tool that came across sites that were new, my own up and coming sites, sites that although looked “bad” in design did bring in light traffic and a whole host of others. I didn’t see why I had to go around emailing those sites to remove links or why I had to remove links from my own network because they were labelled as “suspicious”.

  • Nick Stamoulis

    I think your other way of looking at it is a very good angle to approach Penguin from. Penguin started with the worst offenders and is working it’s way through those that are “skating by.” It means that it’s getting harder and harder for sites to cut corners and get away with it.

  • rjonesx

    I think the better explanation here is that Google only analyzed a certain percentage of sites in the first round of Penguin – likely those that are receiving meaningful organic traffic. These sites also tended to have a lot of links. When Penguin was done analyzing them, many lost their rankings and a new batch of sites, likely with fewer links, filled in the rankings. The same Penguin algorithm was applied, perhaps with a few tweaks, and it still caught the same types of links as before. However, the sites it was analyzing in general had fewer links because the worst offenders had already been hit. This will continue to be the case until, like Panda updates, most of us wouldn’t even notice it happen if someone didn’t announce it. The changes in link numbers is not a tightening of the algo, rather a shift in the data set itself.

  • Chris Kramer

    What a confused study. The Fortune 5000 bit is a red herring and has nothing to do with the headline findings. (4 of the top 50 Fortune 5000 sites had at least 40 percent links from “suspicious” pages, and 2 of those may have been penalized by Google.)

    The real study is that they reviewed “several hundred sites” and 250,000 links to penalized sites and 250,000 to non-penalized sites, and attempted to identify the threshold for penalization. And they apparently did this 4 times, though this isn’t listed in the methodology. Also not mentioned if they the same “several hundred” sites or a new batch each time.

  • Field

    Really feel confused about this Panda update, I just keep writing original articles in my site, but it went down recently!

  • tiaispl chd

    Recovery from penguin penalty is not easy but we can say we need to do follow some techniques to avoiding such type of harms. Main thing where we need to focus is why Google penalize you?where is the mistake and how we overcome it? Now a days many website lost his ranking because of penguin, But it does not meant that they never come again on top. I personally know few companies who are working to recover Google penalty websites. But keep in mind one thing recovery time will be longer.

  • Gui

    if you have 50% of spammy links, you probably deserve to be penalised. I don;t really see where the problem is here. To my opinion, it should be even tougher !

  • Lilacor

    Hi, John! I have written a pretty thorough step by step guide on how to recover from Penguin related penalties here: It took me quite some time to collect the whole information, but I think the final result is quite satisfying. I hope you will find it useful too. I have almost coped with one Penguin penalty for on of my clients after 3 months of anchor diversification and building high-quality, relevant backlinks. There’s a way out, but it’s never easy. The domain / brand should deserve the huge work, otherwise it’s not worth it!

  • Wesley Warren

    I just finished a four week campaign to contact webmasters and ask them to change or remove keyword rich anchor links to my niche industry directories. When I run a report in MajesticSEO it shows my exact match anchors are down to 4%. Also I didn’t have any links from link networks or free directories (although my link report did show many links from several directories that I think are just copies of DMOZ, but they are all nofollow so I figure they should be ok)

    - All of my links come from business sites in my market, a few have come from spammy blogs (which I added to my disavow list) – it has been a lot of work because these sites are 10+ years old.

    At any rate, I am really stressed out for a couple reasons

    - 1) While 80% of the 3000 or so people I contacted have been cooperative (many have old email addresses that are bouncing, or disconnected phone numbers) – when I look at the Google Cache of the pages, some are several months old, so even though the links have been removed or the anchor text changed to the domain name, I am not sure how soon Google will even register that change.

    So even if a penguin refresh happens tomorrow, if Google hasn’t indexed all of these link changes and its using pages from 3 weeks ago, my ration might still appear off balance. Since it was always recommended to use keyword anchors, I had a huge percentage of exact match keyword links out there.

    - 2) I can’t seem to figure out if I have to wait until Google sends a manual refresh of the Penguin update OR if penguin just cycles through using the current algorithm and re-evaluates link profiles. I am hoping that Penguin is off running in the background and in a couple weeks the Penguin keyword specific penalty I have will drop off.

    I hate this waiting game, because I’m not sure if I have done enough, and if I haven’t I might have to wait months for the next update!

  • benlanders

    Great, great… so now we’re going to have to waste a bunch of time fending off negative SEO attacks? Great system Goog.

  • Aon Thompkin

    LOL yes indeed good sir, and I might add, all of the algo tweaks are quite premeditated, which in itself sparks the obvious question:

    Who do you suppose owns the sites that keep “filling in the rankings?”


    The more we read about these “updates” the more I keep wondering “who” has had time to “fill in” with pre-conceived guidelines and advance notice, the blanks that will clearly become available!

    Conspiracy theory? MAYBE,…. but for sure an entirely feasible scenario given a modicum of reasonable thought.

    When one can be both the measuring stick of the infraction yet to be imposed AND the executioner, the degree of culpability increases MANY fold.

    Yeah, I said it!

    Aon (painting the target on my forehead) Thompkin

  • Ranking Signals

    @Chris – They looked at the Inc. 5000 NOT Fortune 5000! (Do SEO people ever watch or read traditional business news??)

  • Florian

    True, although lowering the level that dramatically would make negative SEO extremely easy. 10% sounds much, but also keep in mind the legions of scrapers, pseudo whois sites and similar. For a huge, established site they won’t ever hurt, but for a small business or newer sites with very few backlinks, those automatically generated low quality links easily exceed 10%.

  • Stacie Walker


    Excellent post. It is fine with me that strictness has been enforced. It keeps the spammers away and allows the businesses that add true value on top. Thanks for this important information.

    Stacie Walker

  • Jason A. Keeler

    Don’t buy links, don’t create spammy manual links, keep track of who is linking to you, etc. This should never be a problem for any legitimate, professional SEO. If you are cleaning up an old mess, we’ll, that’s probably the end result of being a spammer. I have yet to hear of an unwarranted penalty…

  • Lilacor

    Hi again! Well, I have read such information, yes. Some SEOs claim that only the next Penguin update will show signs of recovery for the post Penguin victims. I also think there’s something truth in this theory, but it’s not 100% true as I successfully recovered 2 penguinized sites (they got 80% of their initial traffic back, which is a good sign), but other 3-4 projects are still showing almost no signs of recovery. So, the truth is somewhere in between as usual. I believe it’s the harshness of the penalty that matters the most here, but it’s quite difficult to establish it, so you will just have to keep trying and wait for Penguin 4 to come.

  • Phil Graham

    If a site has been hit by Penguin, do SERPs drop off a cliff, or is a drop of only two or three places in search results possible? I’ve noticed a fall-off in traffic since October but little change in SERPs for 30-odd keyword phrases that I monitor.

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