Image source: II-VI.

What: Shares of engineered material and opto-electronic component manufacturer II-VI (NASDAQ:IIVI) declined on Wednesday, one day after the company's third-quarter earnings report propelled the stock higher. At 2:45 p.m. ET, shares of II-VI were down about 10%.

So what: II-VI's third-quarter results were generally positive. The company reported non-GAAP revenue of $200.9 million, up 10% year over year and about $8 million higher than the average analyst estimate. Strong 25% growth in the photonics business, as well as a 12% surge in performance products sales, more than offset a decline in the laser solutions segment. However, acquisitions in that area led total laser solutions revenue to grow slightly year over year.

Non-GAAP EPS was $0.35, up 52% year over year and $0.07 higher than analysts expected. Non-GAAP bookings totaled $233.3 million during the quarter, up 19.2% year over year, growing significantly faster than revenue.

Shares of II-VI surged on Tuesday due to the company's report, closing about 5.5% higher. That gain was more than undone on Wednesday, though, with no new news driving the decline.

Now what: One thing that could be giving investors pause is II-VI's guidance. The company expects revenue to grow during the fiscal fourth quarter, with revenue excluding acquisition effects expected between $200 million and $210 million, up from $196.7 million during the prior-year period. But non-GAAP EPS is expected to decline year over year, with the company guiding for a range of $0.22 to $0.24, compared to $0.27 in the prior-year period. Excluding acquisition effects, EPS is expected to be roughly flat year over year.

It's impossible to say exactly what caused the decline in the stock today, but II-VI CEO Francis Kramer expects a strong fourth quarter:

With our acquisitions and investments to commence next quarter, we are accelerating the build out of a scalable semiconductor VCSEL laser platform. II-VI Photonics delivered a robust quarter, particularly from the optical communication markets. Our record bookings this quarter indicate that we expect to end the fourth quarter strong.