SanDisk just reported a 251% revenue jump, crushed Wall Street's expectations on both revenue and earnings, and the stock dropped 6% after hours. If you're confused, welcome to the club. Let me explain what's actually happening here.

The numbers were spectacular. Revenue hit $5.95 billion versus $4.73 billion expected. Earnings per share came in at $23.41 versus $14.66 expected. That's not a beat – that's a blowout. The company even guided higher for next quarter.

So why did the stock tank? Because expectations versus results is only half the equation. The other half is what happened before the report.

Here's the thing retail investors need to understand: the smart money doesn't wait for earnings to react. They front-run the news. If hedge funds and institutional investors expect a strong quarter, they buy weeks or months in advance. By the time the actual earnings hit, they're already sitting on gains – and they use the good news as an opportunity to take profits.

SanDisk is a perfect example. The stock had already run up significantly heading into earnings. Wall Street analysts had been upgrading the company for weeks, citing tight NAND supply, strong AI infrastructure demand, and the upcoming ramp of their BiCS8-based QLC enterprise SSDs. The thesis was well-known.

When the earnings came out and confirmed everything the market already believed, there was no reason to buy more. Instead, investors who bought early took their profits. That selling pressure outweighed any new buyers coming in on the good news.

This is what's often called "buy the rumor, sell the news." It's not that the news is bad – it's that the news was already priced in.

Another factor: forward guidance matters more than backward results. SanDisk guided Q4 revenue to $7.75-$8.25 billion, which is strong. But some analysts may have been hoping for even higher guidance given the strength of AI demand. If expectations were for $8.5 billion and they guided to $8 billion, that's technically a "miss" even though it's a huge number.

Here's the practical takeaway for retail investors: . If a stock has already run up 30-40% heading into earnings, the good news is likely priced in. You're not early – you're late. The people making money bought months ago when no one was paying attention.