Volatility is growing in the stock market among AI-related companies. Swings are widening beyond AI chip and model developers and cloud computing companies to stocks of firms supplying parts needed for AI data centres, as well as raw material prices. Shares are also seen jumping or plunging in a single day.

On Jan. 6, Sandisk shares, a company known for NAND flash memory, jumped 27 percent. In connection with that, The Information said there was no clear reason other than a Morgan Stanley report that the increase in NAND flash memory prices would be larger than expected.

Demand for NAND flash memory has risen sharply in recent months on the back of the AI data centre boom, leading Sandisk shares to keep climbing. Sandisk shares rose 559 percent last year and the uptrend continued this year. They jumped 47 percent in only the first three trading days of 2026.

Nvidia's moves also had a positive impact on Sandisk's share rise. Bank of America analyst Wamsi Mohan referred to Nvidia CEO Jensen Huang unveiling a new chip at CES2026 in Las Vegas that is designed to handle a larger context window through a dedicated storage tier linked by Nvidia BlueField-4. He said NAND flash was emerging as a more important layer in AI inference.

Based on TrendForce data, NAND flash prices rose 20 to 30 percent in the fourth quarter from the previous quarter, and were forecast to rise by more than 30 percent additionally in the first quarter.

Some companies are smiling on share gains driven by the AI craze, like Sandisk, but others are suddenly left frowning. Each time influential companies in the AI arena, including Nvidia, upgrade technology and products, fortunes appear to diverge for related firms. Recently, data centre cooling equipment companies were hit by a single comment from Nvidia CEO Jensen Huang.

Bloomberg News reported that after Huang said on Jan. 5 that Nvidia's new AI server rack products would not require external cooling equipment, investors sold shares of companies such as Modine Manufacturing and Johnson Controls.

These companies had been seen as beneficiaries of the expansion of AI data centres until recently, but the mood has now changed. In Modine's case, which last year announced a plan to significantly expand its manufacturing base in the United States to target the data centre market, its shares fell 7.5 percent on Jan. 6 alone.

Given Huang's remarks, copper prices also look likely to keep climbing. At CES2026 in Las Vegas, Huang said Nvidia's new AI chip racks include 2 miles, or 3.2 km, of copper cable. He stressed that copper is the best conductor we know.

According to a Reuters report, copper prices surged last year due to data centre demand and this trend is expected to become more pronounced due to Huang's remarks.

Rising copper prices are not good news for data centre developers, and not for the overall economy either. The same applies to rising prices for NAND flash, which is widely used in smartphones and laptops. Morgan Stanley forecast that rising NAND flash prices are likely to increase smartphone makers' costs, making it highly likely to lead to higher smartphone prices.