What just happened? We've been hearing for a while now that AMD is continuing to chip away at Intel's dominance of the CPU market, but according to a new report, the trend reversed in Q4 when Chipzilla gained market share for the first time in three years.

Mercury Research's results for the fourth quarter of 2020 show that AMD lost some of its x86 market share despite having a good year overall. In desktop, the company fell from 20.1 percent in the previous quarter to 19.3 percent.

AMD is unlikely to be too concerned about the findings. Its QoQ desktop CPU share might have been down 0.8 percent, but the Q4 result was still a full percentage point higher than the same period in 2019. Moreover, YoY revenue was up 50 percent---the company recorded record financial results last year.

As previous reports have shown, the PC industry is one of several to have been boosted by the pandemic and the resulting increase in those working from home: the x86 CPU market grew a massive 20.1 percent.

AMD's decline is being blamed on the stock issues faced by its Ryzen 5000 processors. As with so many of the holiday season's top tech items, demand has far outweighed supply, leaving many desperate consumers with the sole option of paying exorbitant prices on eBay if they want a Zen 3 CPU. Even some of the Ryzen 3000 line have been experiencing similar issues.

It was the same story in the laptop CPU market. AMD's share fell 1.2 percent QoQ to 19 percent in the fourth quarter of last year, but that's still 2.8 percent higher than in Q4 2019. Don't be surprised if the recently revealed Ryzen 5000 mobile processors help it pull some of that lost share back.

Intel's fortunes were helped by its improved supply of budget processors designed for devices such as Chromebooks. Its CPU shipments increased 33 percent in Q4, and with AMD admitting its shortages may last several more months, Intel could continue to pull ahead, especially with Rocket Lake set to launch in March.

Looking at the CPU market as a whole---including servers, the only area where AMD saw quarterly gains---AMD's share declined 0.7 percent in Q4 to 21.7 percent. Compared to a year earlier, that's still a 6.2 percent increase.

While Mercury Research's report has AMD declining, the latest Steam Hardware Survey shows the company rebounding from a December dip and stealing 3 percent of Intel's processor share last month.