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 Coherent (COHR) plunged today by as much as 14%, after the company reported fourth quarter earnings.

So what: Revenue in the fourth quarter tallied up to $188.7 million, shy of the $195.3 million that investors were expecting. The bottom line missed by even more, with the non-GAAP earnings per share of $0.71 falling short of the $0.85 per share consensus estimate.

Now what: Needham & Company offered up some comments while downgrading its rating on the stock to "hold." Part of the miss was attributed to delays in receiving important components from a vendor in its display business. CEO John Ambroseo said the component delays negatively affected revenues to the tune of $7 million. Microelectronics bookings fell, and first quarter guidance was also soft, which, when combined with the fourth quarter weakness, has sparked a sell-off.

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