SanDisk has been one of the market's biggest winners of the past year, but several parts of the story look weaker under the hood — a warning for anyone buying now.

• The stock is up nearly 40x in a year as memory and storage prices exploded, and revenue jumped almost 5x while costs fell.
• Most of that growth came from raising prices, not selling more — and the company only expects sales volume to grow in the mid-teens going forward.
• Wall Street expects prices to start falling next year, which would flip earnings from fast growth to shrinking, making the cheap-looking 9x earnings multiple misleading.
• A chunk of the factory spending sits in a separate part-owned company, Flash Ventures, so the real capital costs and risks are hidden from the balance sheet.
• Roughly $2 billion of recent "cash flow" was really upfront deposits from big cloud customers, some of it already spent on buybacks — cash that disappears if those orders get cancelled.
• The new high bandwidth flash pitch, framed as a cheaper rival to the pricey memory chips Nvidia buys, was demoed under favorable conditions; flash is far slower for training work, where most AI money is actually going.

Outlook: The stock can keep running while prices stay hot, but if selling prices roll over next year the growth story depends entirely on high bandwidth flash — which is being built with SK Hynix, so SanDisk would share the upside anyway.