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 ADTRAN (NASDAQ:ADTN) have run higher today by as much as 15% after the company reported first-quarter earnings.

So what: Revenue in the first quarter was $143 million, topping the $139.8 million that the Street was expecting. That top-line beat translated into an even bigger bottom-line beat, with adjusted earnings per share of $0.17 easily besting the $0.08 per share that investors thought was in store.

Now what: CEO Tom Stanton said that the company's domestic carrier business was getting stronger, and international sales helped the company put up a sequential revenue increase. ADTRAN also announced a $0.09 per share quarterly dividend. Jefferies analyst George Notter isn't impressed though, keeping an "underperform" rating and citing intensifying competition that could lead to market share losses.

Interested in more info on ADTRAN? Add it to your watchlist by clicking here.

Fool contributor Evan Niu, CFA, has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.