Google December 2025 Core Update – Information and Analysis

Steve Paine

(Author)

Published: 12.12.2025

Modified: 16.01.2026

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• Google’s status page for the Core Update Start date: 11th December 2025. End date: 29th December 2025
• For detailed information and data on all previous Google updates, see the SISTRIX update tracking page

Google did not provide any additional information about which parts of the search algorithm will be improved with this core update.

Timeline of Change, UK and US search

The Google Update radar shows the timeline of changes in the SERPs. The SISTRIX Pin has been set for the 16th December which is a day after the first changes seen in our data.

An automatic pin has been added to graphs for the 15th December. This will show in Visibility Index graphics if major changes are detected in the same week as the pin.

Data and Analysis

An increase in the amount of changes in the SERPs was first seen in data from the 14th to the 15th in SISTRIX and has continued to develop strongly since then.

Winners and losers appear across reference, informative and ecommerce sites. The table below shows a selection of over 400 domains that have shifted in significant percentage or absolute values, up and down.

Domains from health, finance, reference, travel and adult topics can be seen in both winners and losers.

Fashion retail has also been churned:

• shein.co.uk +120.0%
• riverisland.com +38.0%
• boohoo.com +61.7%
• prettylittlething.com +33.5%
• vinted.co.uk +386.8%
• ever-pretty.co.uk +147.3%
• very.co.uk +20.6%
• zara.com +26.4%
• hm.com -27.2%
• asos.com -9.9%
• marksandspencer.com -7.3%
• debenhams.com -28.4%
• next.co.uk -5.1%

Vinted still on the rollercoaster +386.8%

One of the established domains and brands that benefited from a huge boost in this Core Update was vinted.co.uk. The domain is a great example of one that lives near the edge.

As you can see from the historical VI below it has been unstable since the product reviews update of 2023.

The domain contains many elements of a review site with ratings on each product and each user. The format of each page is fixed and there’s very little descriptive text. The ads also send the signal that this isn’t a brands D2C website.

Given that the domain both wins and loses on a regular basis we suspect that the SEO is constantly trying to bring the site to the positive side of the line. Over the last three years the area under the curve has certainly increased but it’s failing to ‘lock-in’ the gains.

Automotive

Like Vinted, automotive sales platforms also have the potential issue of looking like a cookie-cutter website containing the same information as competitors and as such, one can expect the best commercial sites to be working at or beyond the limits of what Google finds good.

Stonacre.co.uk saw a good boost during the December Core Update but wasn’t the only car-related site that shifted:

Adult

The UK Online Safety Act changed the rules for, among others, websites dealing with adult entertainment. All affected websites needed to make changes for compliance during 2025 which means there could be ‘walls’ going up which not only affect current rankings but may affect how a site is assessed in a core update.

• xhamster.com -13.2%
• xhamster2.com -40.1%
• x.com -21.9%
• sexvid.xxx -58.9%

Remember that Google will always provide answers to adult queries if the user wants them so there’s always space for the providers of that information. Where one site gains, another wins.

• xnxx.tv +69.1%
• xvideos2.com +66.3%
• xvideos3.com +53.7%
• xvideos.com +10.1%

Xvideos have gained across what is assumed to be three variants of the website, but this could be due to losses at the competitor websites.

US Data

Lily Ray has used SISTRIX data in an extensive analysis of the changes, by sector, in a post over at the Amsive Digital website. One point that is mirrored in the UK too is that of news media websites. “News publishers also continued their challenging trajectory, with several major outlets in our analysis declining during the rollout.”

Use free tools from SISTRIX

We provide a number of tools that allow you to check your own domains and the effects of a Core Update. A 14 day free, no-commitment trial with all data and tools: is available.

Google Update and Feature Update Radar

The daily view on SERP updates can always be viewed in our Google Update Radar which shows the current level of movement relative to the last 90 days. The radar graphics are an indicator of SERPs changes across 1 million SERPs every day.

The feature update radar (below the main radar on the same page) gives you an overview of any major SERP format changes that might have occurred. Features changes will impact CTR and therefore click-rates.

Free algorithm check tool

You can check domains against all Core Updates by using the free Google Updates Check tool. Enter a domain and we’ll check it against 15 years of recorded Google Algorithm Updates. Results are returned in about a minute.

VI Check Tool

To instantly see the live Visibility Index and VI Rank for a domain, use this tool.

What to expect in a core update

Core Updates can have major business-level impact for the digital commerce sector. In the June 2025 Core Update, for example, Nordstrom lost over 29% of their website visibility in US organic search and put the domain on trajectory to lose over 70% in three months. WhatCar (co.uk) lost 29.4% of Visibility in just 2 weeks in the UK.

Gains can be made, of course. Dunelm put on 17% during the same Core Update and nearly doubled their organic visibility in the following months. It was a good 2025 for their SEO team.

The sequence of events usually include early commentary from the SEO community but data is rarely available until the second or third day after the announcement. Be careful of reports of domains that are shifting – there are always large-scale domain movements happening and these can have an impact on closely related domains. For example the following domains are making major changes to their presence in the UK during the December Core Update.

• mountsinai.org – content move
• visittheusa.co.uk – content move
• cats.org.uk – content move
• actionfraud.police.uk migration to reportfraud.police.uk
• thekennelclub.org migration to royalkennelclub.com

How to check for domain changes during a Google Core Update

Firstly, understanding the Visibility Index is going to help you. The VI is a transparent and well-defined KPI that can be used at any level of a domain. For example, you can monitor your informational content directory, or the eCommerce directory in your website. The domain overview tutorial will help you to access this information in the toolbox.

Automatic pin indicators in SISTRIX

The SISTRIX change detection pins will show automatically if there have been significant changes near to the date of the pin. You can also set your own pins.

For agencies. Set up a live dashboard of your customer domains.

For company owners. Set a Visibility Index alert that reports to Slack or Email. You can also check a domain for free on our VI check tool.

For prospectors and stakeholders/investors. Watch the losers list. Data from 12th December is show in the image below. Click to access (free trial.)