What happened

Shares of Finisar Corporation (NASDAQ:FNSR) were down 20% as of 12:15 p.m. EST Friday, after the optical-communications-equipment company released disappointing fiscal third-quarter 2017 results.

So what

Quarterly revenue climbed 23.1% year over year, to $380.6 million, driven by strong demand for 100G transceivers, as well as for wavelength-selective switches and ROADM line cards. On the bottom line, that translated to adjusted net income of $67.2 million, or $0.59 per diluted share, up from $26.6 million, or $0.25 per diluted share in the same year-ago period. But analysts, on average, were looking for higher revenue of $389.6 million, and adjusted net income of $0.62 per share.

Blue network cables plugged into a router

IMAGE SOURCE: GETTY IMAGES.

Now what

Finisar told investors it expects current-quarter revenue of $360 million to $380 million (up from $318.8 million in last year's fiscal Q4), which should translate to adjusted earnings per diluted share of $0.50 to $0.56. Here again, Wall Street's models were more optimistic, calling for adjusted earnings of $0.58 per share on revenue of $393.4 million.

That's not to say Finisar's growth isn't impressive. But given its underperformance relative to investors' expectations, and with shares still up more than 90% over the past year, it's no surprise to see Finisar stock pulling back today.

Steve Symington has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.