What happened

It was a volatile year for Sprouts Farmers Markets, Inc. (NASDAQ:SFM), but in the end, the organic grocery chain finished with solid gains, up 29% according to data from S&P Global Market Intelligence. Still, the company's performance was anything but consistent as the stock moved wildly on earnings reports and acquisition news and rumors.

The chart below shows the swings back and forth over the year. 

SFM Chart

SFM data by YCharts.

So what

Sprouts' first big move came on March 16-17 as the stock jumped 16% in a two-day span in response to rumors that privately held Albertson's could take over Sprouts. News reports later confirmed that the two supermarket chains held preliminary talks about a combination, but we now know the talks never advanced.

The entrance to a Sprouts Farmers Market

Image source: Sprouts Farmers Market.

Then in June, the stock plunged 15% over a two-day span after rival Kroger, the country's largest traditional grocer, delivered a terrible earnings report, casting doubt on the entire supermarket industry. The next day, Amazon announced its acquisition of Whole Foods, sending shockwaves through the industry as Amazon is known for leveling margins when it enters a new sector.

After recovering those losses, Sprouts took it on the chin again in late August when Amazon completed its acquisition of Whole Foods and announced immediate price cuts in several major categories, making its scorched-earth strategy clear. Since Whole Foods also specializes in organics and healthy food, Sprouts could have the most to lose from an increase in traffic to the Amazon subsidiary. 

Finally, the stock got a spark when Sprouts delivered a strong third-quarter earnings report with comparable sales up 4.6% and an increase in full-year guidance. It also reassured investors as it was its first quarterly report since Amazon took over Whole Foods. Momentum carried the stock higher over the rest of the year. 

Now what

While the late rally made the year a winner, Sprouts has still been a disappointment since its IPO nearly five years, as shares are down significantly. Still, the threat from Amazon seems to be exaggerated as other grocery stocks have bounced back also over the last few months. If Sprouts can keep up its momentum from the third quarter, 2018 could be a rewarding year as well.

John Mackey, CEO of Whole Foods Market, an Amazon subsidiary, is a member of The Motley Fool's board of directors. Jeremy Bowman owns shares of Kroger. The Motley Fool owns shares of and recommends Amazon. The Motley Fool has a disclosure policy.