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 NeoPhotonics Corp. (NYSE:NPTN) plunged nearly 20% Thursday after the company reported solid revenue growth, but also issued downbeat forward guidance, and told investors to expect delays in filing its latest Form 10-Q.

So what: Quarterly revenue is expected to rise 16.1%, to a record $76.8 million, which beat estimates for sales of just $76.23 million. However, NeoPhotonics also stated that fourth-quarter revenue should be in the range of $70 million to $76 million, the midpoint of which is well below expectations for sales of $76.06 million.

In addition, NeoPhotonics worried investors by stating it would not be able to file its latest Form 10-Q on time, thanks primarily to the previous handling of a real estate registration tax of roughly $0.5 million, which was previously categorized as a component of the purchase of property, plants, and equipment from LAPIS Semiconductor. Upon further examination, the company concluded it will need to restate its first and second quarter financial statements to expense the tax as an acquisition cost.

Now what: The net result, NeoPhotonics says, will be a "decrease in cash flows from operating activities of approximately $0.5 million, an increase of cash flows from investing activities of approximately $0.5 million, and an increase in loss before income taxes of $0.5 million in the first quarter of 2013 and the six months ended June 30, 2013."

Seems fair enough, and it should also come as no surprise that NeoPhotonics announced it has replaced its existing independent auditor with the firm Deloitte & Touche as of November 15, 2013.

Even so, once its accounting issues are all hammered out, I'll still find it hard to justify buying shares of NeoPhotonics when they trade at nearly 150 times next year's estimated earnings. Until the company can prove it not only has its books figured out, but also has what it takes to achieve sustained long-term profitability, you'll find me on the sidelines.

Fool contributor Steve Symington 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.