SanDisk RSI Hits Record 99, Fueling AI Bubble Fears Across Markets

SanDisk Corporation (NASDAQ: SNDK) has posted a monthly Relative Strength Index reading above 99, a level that analyst Lark Davis says no publicly traded stock has ever reached.

The extreme reading arrives as SNDK shares rose over 780% year-to-date in 2026 and more than 5,400% since the company spun off from Western Digital in February 2025. The stock now trades near $2,138, a long way from its IPO price of approximately $38.50.

What Is Pushing SanDisk RSI to Historic Levels

SanDisk became a pure-play NAND and solid-state drive company when it separated from Western Digital in early 2025. The spinoff timing proved ideal. Hyperscaler spending on AI infrastructure pulled enterprise SSD demand into a sustained multi-quarter rally, and SanDisk’s revenue grew 251% year-over-year in its most recent quarterly report.

SanDisk monthly RSI above 99! Wild. pic.twitter.com/jORkO9jyQJ

— Lark Davis (@LarkDavis) June 15, 2026

The RSI is a momentum oscillator that runs on a scale of zero to 100. Readings above 70 typically signal overbought conditions, prompting traders to consider reducing exposure. A reading above 99 sits well beyond that threshold and suggests buying pressure at SNDK has reached a level that most technical frameworks cannot meaningfully interpret.

AI Bubble Fears Grow as SNDK Momentum Peaks

The record SanDisk RSI has reignited debate over whether the rally reflects durable demand or speculative excess. Critics draw comparisons to the dot-com era, where valuations detached from revenue reality before a sharp reversal.

Broader AI revenue bubble concerns have spread through the tech sector in 2026, with some analysts flagging circular cloud-spending patterns as a structural fragility. Ray Dalio has separately warned of AI liquidity risks that could force investors to liquidate paper gains when debt obligations come due.

Bulls argue the underlying demand is structural, not speculative. AI training and inference workloads require high-density, fast-access storage, and NAND remains the only technology capable of serving that need at scale. The AMD and Intel overbought RSI surge earlier in 2026 extended well past standard warning signals before momentum stalled, a data point that SNDK advocates cite as a precedent.

A comparable AI stock rally that pushed past 5,100% eventually gave back roughly 35% of its gains. Whether SanDisk follows a similar arc will likely depend on whether hyperscaler capex commitments hold through the back half of 2026.