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 GT Advanced Technologies (NASDAQOTH:GTATQ) initially fell as much as 10% early Thursday, then partially recovered to trade down around 4% after first-quarter results came in below expectations.

So what: Quarterly revenue fell 61% year over year to $22.5 million, which translated to a wider adjusted net loss of $0.22 per share. Analysts, on average, were expecting a slightly smaller loss of $0.21 per share on sales of $26.98 million.

But GT Advanced Technologies offered some solace to shareholders by reiterating guidance for full-year 2014 revenue in the range of $600 million to $800 million, with adjusted gross margin of 25% to 27%. This should result in adjusted earnings per diluted share in the range of $0.02 to $0.18. For reference, the midpoint of both ranges is roughly inline with analysts' expectations for 2014 earnings of $0.10 per share on sales of $694 million.

Now what: That's not to say it should come as any big surprise. After all, last quarter GTAT told investors 85% of this year's revenue will arrive in the second half. And given the near-term absence of a meaningful rebound in the photovoltaic market, it's no mystery the big driver of that top-line guidance is GTAT's multiyear sapphire production agreement with Apple. Under that agreement, the Cupertino-based tech giant is leasing to GTAT a new 700-employee manufacturing facility in Mesa, Arizona.

The deal also involves Apple fronting $578 million in prepayments -- of which GTAT has already received $440 million -- to fund GT Advanced Technologies' capital outlays related to the facility. In any case, while we can't be exactly sure yet how Cupertino plans on utilizing GTAT's increased sapphire capacity, it appears everything is still progressing nicely. As a result, today's pullback might just represent a fantastic opportunity for long-term investors to start or add to a position.

Steve Symington owns shares of Apple. The Motley Fool recommends Apple. The Motley Fool owns shares of Apple. 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.