Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of semiconductor probe cards maker FormFactor (NASDAQ:FORM) fell as much as 15% on Tuesday morning on very heavy trading volume. The big swing appears to be a reaction to rumors of major FormFactor customer Micron Technology (NASDAQ:MU) exploring a sale to Chinese tech giant Tsinghua Unigroup.

So what: FormFactor's chip testing tools are an important piece of Micron's manufacturing workflow. Micron represented 15% of FormFactor's sales volume in 2014, up from 12% in 2013. If that company moves under the control of a Chinese conglomerate with its own preferences and supply chains, FormFactor could lose its third-largest customer. That's never good news.

FormFactor Wafer Probe

FormFactor's future depends on chip builders needing these wafer probes. Image source: FormFactor.

Now what: The Micron risk is real, but there are plenty of not-too-solid assumptions baked into this price drop. If any one of these expectations turn out to be false, FormFactor shares should recover quickly.

In particular, Micron is not very likely to go Chinese. Tsinghua's offer is almost embarrassingly low and very likely to be turned down by Micron's shareholders. And that's only if the bid gets past regulatory reviews, which is hardly guaranteed when a Chinese company looks to spend $25 billion to take over an all-American business.

Furthermore, if Micron accepts the Tsinghua bid and the deal overcomes a plethora of hurdles, the company may still stick with the FormFactor tools it already knows.

FormFactor lists consolidation in the semiconductor industry as a major business risk, and investors are taking that warning seriously today. Just a bit too seriously, in my opinion. This drop is not likely to last, especially is Micron's reported deal evaporizes.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.