Google has defended recent changes to its search system that reduced the prominence of some popular websites.
One of the worst hit by the “Panda” update was Ciao.co.uk, a Microsoft-owned company that had been leading an EU competition case against Google.
Its web visibility fell by 94% according to analysis by Searchmetrics.
Google’s head of search evaluation, Scott Huffman, said it was “almost absurd” to suggest that the results were rigged.
The company regularly changes the algorithms that determine what users see when they search.
Such updates are often done to weed out “content farms” – websites that copy material from other sites in order to get hits.
Where a keyword search may previously have returned their site on Google’s first page, afterwards it may be relegated to further down the rankings.
When the update, known as Panda, was rolled out globally on 11 April, Google published a blog post explaining that it was designed to “reduce rankings for low-quality sites”.
Shopping and price comparison sites such as Ciao.co.uk sometimes suffer when Google algorithms change because they carry comments and reviews replicated elsewhere on the internet.
However, experts said that it was unusual to see a legitimate website hit as badly as Ciao.
“A 94% drop is astronomical,” said Sanjay Shelat, a search engine optimisation (SEO) specialist at Edit Optimisation.