What happened

Shares of Tower Semiconductor (NASDAQ:TSEM) dropped on Thursday following the analog integrated-circuit manufacturer's fourth-quarter report. Results were mixed, with revenue missing expectations. The company's guidance for the first quarter also missed the mark. The stock was down about 10% at 3:50 p.m. EST.

So what

Tower reported fourth-quarter revenue of $357.6 million, up 5.1% year over year but about $0.5 million below the average analyst estimate. Revenue was $1.39 billion for the full year, up 11% compared to 2017.

A TowerJazz clean room.

Image source: Tower Semiconductor.

Fully diluted non-GAAP earnings per share (EPS) came in at $0.58, up from $0.52 in the prior-year period and $0.04 higher than analyst expectations. Free cash flow was $44 million for the quarter, up from $39 million in the prior-year period. For the full year, free cash flow totaled $191 million, up from $118 million in 2016.

"2017 was the best year for the Company to date, as seen in the across the board record financial results, as well as, and maybe more importantly, the realization of several key strategic initiatives, providing a palpable foundation for growth well into the next decade," said Tower CEO Russell Ellwanger.

Now what

Tower expects to produce first-quarter revenue of $325 million, plus or minus 5%. This fell short of the $346.7 million analysts were expecting.

The company put up solid results in the fourth quarter, but soft guidance was enough to send the stock tumbling.

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