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 Finisar (NASDAQ:FNSR) have gained nearly 15% today after the company announced that its fiscal first quarter (ending in July) will be above earlier expectations -- both its own and Wall Street's. The company so impressed the market that trading had to be halted following the early surge.

So what: Finisar's preliminary first-quarter guidance now pegs its revenue at $266 million, above both the analyst consensus of $253.4 million and the former high end of its guidance range, which had been $245 million to $260 million in revenue. Finisar also expects its earnings per share to be either $0.30 or $0.31, well ahead of Wall Street's $0.24 consensus and its own previous range of $0.22 to $0.26.

Finisar also notes that its (preliminary) record-setting revenue rose primarily on strong sales of Ethernet transceivers, which helped push gross margins up from the previously estimated 33% range to a range of 34.5% to 35%.

Now what: Finisar's had a strong summer, as its stock is now up 60% in the past three months. However, there's nothing here that indicates a screaming buy -- Finisar is still losing money on an officially reported trailing 12-month basis, and its most recent free cash flow figures give it a price-to-free-cash-flow ratio of about 35.7 after the pop. There could be more growth ahead, but there might also not be -- Finisar's earnings history shows a lot of ups and downs in earnings and free cash flow.

Want more news and updates? Add Finisar to your watchlist now.

Fool contributor Alex Planes 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.