Micron shares dropped 5.5% in the first five minutes of trading Monday, and that, in a nutshell, is the news. If you were hoping for a satisfying explanation underneath it, The Motley Fool's writeup traces the move back to a report from tech news site WCCTech, which, and I want to be precise here, reported that Micron's stock had dropped.

Read that again slowly. A news story about a stock decline, which then contributed to the stock decline. It's the financial equivalent of a dog chasing its own tail, except the dog is a publicly traded company that thousands of people own in their retirement accounts.

I don't say this to mock WCCTech or The Fool. They reported what happened, which is their job. What I find interesting, and what I'd want you to take away from a morning like this one, is how little it takes to move a stock that has already been wobbling. The memory business is cyclical, sentiment in cyclical names is fragile, and when a stock has been leaning one direction, any headline becomes a shove.

The math on a 5.5% drop is simple enough to do in your head. If you owned $10,000 of Micron, you watched about $550 evaporate before your coffee finished brewing. If you owned it inside a broad index fund, which is how most of you should own something like Micron if you own it at all, your total portfolio probably moved a fraction of a percent. Same company, same news, wildly different mornings.

In one paragraph, you have the whole argument for diversification. Not the textbook version, the lived version.

Now, none of this means Micron is a bad business. My own view is that memory and storage demand is real, and that AI data centers have been putting real strain on DRAM supply, though that's my read of the space rather than something anyone proved this morning. But a 5.5% move on a story about the story tells you the buyers and sellers in that stock this morning weren't weighing intrinsic value with a calculator. They were reacting. Somebody hit a sell button, a chart turned red, a site covered it, and the next somebody hit a bigger sell button.

I lived through October 1987, the dot-com unwind, 2008, and March of 2020. I've watched days where the reason for a drop was serious and days where the reason was, frankly, mush. The market doesn't distinguish between those two very well in the moment. It only sorts them out later, and usually at a volume level most of us can't hear over the noise.

So what should you do with a morning like this? If you own Micron as a deliberate position, ask the same question I always ask: does the price today compensate you for the specific risks of a cyclical memory business? Nothing in a five-minute dip answers that. If you own it through a total market fund, do what I do, which is nothing at all, pleasantly.

And if this morning tempted you to sell in a hurry, that's worth sitting with. Quick moves on thin reasons are how patient investors turn into panicked ones. The price will keep making noise. Your job is to decide, in advance, which noise deserves your attention.

As always, this is my perspective after forty years of managing my own money, not professional financial advice.