The world’s three biggest makers of computer memory are facing a class action lawsuit accusing them of working together to limit RAM supply and push up prices. According to a report from Law360, the lawsuit was filed on behalf of a group of individual and business consumers against Samsung, SK Hynix and Micron, the companies that together produce nearly all of the world’s DRAM chips.

The lawsuit claims the three manufacturers cut back on production of older DDR3 and DDR4 memory, the type commonly used in everyday consumer devices, and shifted their focus toward high bandwidth memory, or HBM. This type of memory is more expensive to produce but is in high demand from AI data centres. The complaint argues this shift was coordinated between the three companies rather than something that happened naturally through normal competition.

The filing states that in a properly competitive market, rising prices for a product should encourage at least one manufacturer to increase output to take advantage of the higher prices, which would then pressure competitors to do the same or risk losing business. The lawsuit claims this did not happen in this case, and instead all three companies moved in the same direction at the same time.

According to the complaint, ordinary consumers and businesses buying conventional DRAM, along with the products that use it, have ended up paying higher prices as a result of this reduced competition in the market.

The lawsuit also points to the difficulty other companies would face trying to enter the DRAM market and challenge the three existing manufacturers. It states that building a single DRAM fabrication plant can cost tens of billions of dollars and take years to complete. It also notes that the manufacturing process relies on years of accumulated technical knowledge, and that US export rules prevent newer chipmaking equipment from being sold to manufacturers in China, making it harder for outside companies to compete.

This is not the first time Samsung, SK Hynix and Micron have faced accusations of price fixing in the DRAM market. In 2005, Samsung pleaded guilty and paid a $300 million fine following a US Department of Justice investigation into an international price fixing conspiracy in the DRAM market. SK Hynix also pleaded guilty at the time and was fined $185 million, while Micron avoided a fine after reporting the matter to investigators and cooperating with the case. The three companies were investigated again by Chinese authorities between 2016 and 2018 after another period of rising prices, and the new lawsuit describes the current situation as a third instance of similar behaviour involving the same companies.