As 2011 comes to a close, it's a great time to look back at what happened to the stocks that interest you. By making sure you know the important things that a company accomplished -- as well as the setbacks it experienced -- you can make a better decision about whether it's a smart investment for your portfolio.

Today, let's take a look at ZAGG (Nasdaq: ZAGG). As a provider of accessories for handheld devices, ZAGG's fortunes rise and fall with the companies that make those devices. This year, the stock zigged and zagged dramatically before settling down to a nice gain for the year. Below, I'll take a closer look at the events that moved ZAGG's shares this year.

Stats on ZAGG

Year-to-Date Stock Return 12.2%
Market Cap $253 million
Total Revenue, Trailing 12 Months $141 million
Net Income, Trailing 12 Months $11.7 million
1-Year Revenue Growth 141.6%
1-Year Profit Growth 71.8%
Short Interest (% of float) 50.2%
CAPS Rating (out of 5) *

Source: S&P Capital IQ.

What was up with ZAGG this year?
ZAGG's big product is its invisibleSHIELD, a clear film that protects smartphone screens from scratches. The company also sells a wide range of other protective accessories. Given the rise of Apple's (Nasdaq: AAPL) popular smartphones and other handheld devices, ZAGG has an ever-increasing potential market for its products. ZAGG has a close relationship with retailer Best Buy (NYSE: BBY), which accounts for a huge percentage of its total sales.

But many are skeptical of ZAGG's prospects going forward. Along with SodaStream (Nasdaq: SODA) and Travelzoo (Nasdaq: TZOO), ZAGG is among just a handful of companies with more than half of its shares sold short.

Still, ZAGG doesn't seem to care about the shorts. It partnered up with Logitech (Nasdaq: LOGI) to sell a keyboard case for Apple's iPad 2, and with products for non-Apple providers like Motorola Mobility and Research In Motion (Nasdaq: RIMM), ZAGG has all its bases covered.

Investors should expect continued volatility for the stock in line with how the smartphone industry does. But despite the zigs and zags, as long as handheld devices exist, ZAGG has a good chance of making money from them.

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This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.