Caterpillar stocks have lost 17 percent of their value in the the last five days.
That's an average decline of nearly 3.5 percent daily.
Many investment brokers are saying there is no real explanation for the sudden plummet and that it will be back on the rise.
So what does such a steep drop mean for local investors?
"Caterpillar over the long haul is going to be fine," says Brad McMillan with the Institute for Principle Leadership at Bradley University. "This really affects everybody. Anybody who has a retirement account is seeing their savings that they've built up over a lifetime go down significantly."
Former Peoria Mayor Dave Ransburg says, "These are very difficult economic times. Our economy spent a long time coming back. There's concern about a double dip recession, unemployment is still high, we're not adding new jobs. It's concerning."
Last month, Caterpillar boosted its profit forecast for the year.
A company spokesman says the company stands by the projection.