Storage and mass storage device companies were the best performers in the S&P 500 index last year. As huge sums of money invested in AI infrastructure construction infiltrate some of the traditionally stable sectors of the technology industry, this sector has risen along with it. This group, led by SanDisk, Western Digital, Seagate, and Micron, remained at the top of the index in early 2026. SanDisk rose 16% on the first trading day of the year, then surged 28% on Tuesday. The stock rose 1.1% on Wednesday, with a cumulative increase of 49% over the first four trading days of this year. Meanwhile, Western Digital, Seagate, and Micron all recorded double-digit percentage gains at the start of 2026, although all three stocks declined on Wednesday. Peter Andersen, chief investment officer of Anderson Capital Management, said that considering the AI data center construction narrative, the recent strong momentum is visually reasonable, but he is increasingly concerned that the market is excessively extrapolating future demand and underestimating historical cyclicality, as well as the risk of overcapacity and price pressure. This rally may be difficult to maintain in the short term. For example, SanDisk and Micron's 14-day Relative Strength Index were both above 70. Some technical analysts think this is a sign that stocks are overbought.

Storage and mass storage device companies were the best performers in the S&P 500 index last year. As huge sums of money invested in AI infrastructure construction infiltrate some of the traditionally stable sectors of the technology industry, this sector has risen along with it. This group, led by SanDisk, Western Digital, Seagate, and Micron, remained at the top of the index in early 2026. SanDisk rose 16% on the first trading day of the year, then surged 28% on Tuesday. The stock rose 1.1% on Wednesday, with a cumulative increase of 49% over the first four trading days of this year. Meanwhile, Western Digital, Seagate, and Micron all recorded double-digit percentage gains at the start of 2026, although all three stocks declined on Wednesday. Peter Andersen, chief investment officer of Anderson Capital Management, said that considering the AI data center construction narrative, the recent strong momentum is visually reasonable, but he is increasingly concerned that the market is excessively extrapolating future demand and underestimating historical cyclicality, as well as the risk of overcapacity and price pressure. This rally may be difficult to maintain in the short term. For example, SanDisk and Micron's 14-day Relative Strength Index were both above 70. Some technical analysts think this is a sign that stocks are overbought.