SanDisk just learned the hard way what “hot stock meets cold water” feels like.

On Thursday, Nov. 20, newly re-listed SanDisk (SNDK) sank roughly 20% intraday during a broad tech selloff, erasing a chunk of its 2025 gains in a single session. The slump arrived as Wall Street flipped from early green to deep red after Nvidia’s post-earnings pop faded and risk appetite soured. By the close, the Nasdaq logged its lowest finish since September.

If you’re thinking, “SanDisk? Didn’t that get bought years ago?” — yes, and then it came back. Western Digital spun off its flash unit this year; regular-way trading for SNDK began on Feb. 24, 2025. In other words, the SanDisk brand is once again a standalone, public memory maker.

Three pressures hit all at once:

1) A shaky tape. Thursday’s reversal wasn’t just a SanDisk story. Tech leadership cracked across the board as investors questioned stretched AI valuations and digested mixed macro signals. When the tide goes out, high-beta winners usually feel it first — and SanDisk has been one of 2025’s flashiest comeback tales.

2) Cost and capacity jitters. Earlier updates from the company flagged startup costs tied to new fab activity and a softer near-term margin path — not fatal, but enough to make a momentum stock skittish when markets wobble. Traders leaned into those worries as the day unraveled.

3) Mixed read-throughs on NAND. Industry trackers say NAND contract prices are rising, with the potential for double-digit gains into early 2026 as supply stays tight. Rising prices can help producers, but they also invite volatility if customers balk or if investors fear a boom-bust cycle. The narrative can swing quickly from “pricing power” to “demand destruction.”

How (to think about it)

This doesn’t look like a “flash meltdown” so much as a violent squeeze-out in a hot corner of the market. A few lenses to keep handy:

• Context matters. SanDisk’s return to public markets — after Western Digital’s 2016 acquisition — has been eventful, with a powerful run-up and fresh analyst attention (including recent bullish notes). Big moves cut both ways; when the market turns risk-off, names with the most air under them fall the fastest.

• Watch the real economy of chips. TrendForce expects NAND makers to keep nudging prices higher into Q1 as supply remains disciplined. If those hikes stick and end-demand in data centers and devices holds up, producers’ revenue math gets easier. If OEMs push back or inventories build, the story changes.

• Peer signals help. Memory and storage stocks often trade in a pack. Recent bouts of weakness in names tied to flash and storage — amid broader Asia tech jitters — underline that this is bigger than one ticker.

Bottom line: Thursday’s plunge was dramatic, but it fits a familiar pattern — a red-hot spinoff colliding with a risk-off day and some well-telegraphed cost fears. The longer-term plot still comes down to fundamentals: can SanDisk turn today’s tight NAND backdrop into durable gross margins without choking demand? For now, the stock’s violent move says less about a “flash crash” in the business and more about how jumpy this AI-adjacent market has become.