It was a rough year to go public. Volatility in the market made life difficult for companies trying to dip their toe into publicly traded waters. As a whole, initial public offerings were down 9.6% this year. Tech stock IPOs had an especially bad year, falling by an average of 18.4% below their initial offering price by year’s end. Of the 125 U.S. stocks that made their debut in 2011, 71 of them finished below their IPO price.

That said, several companies managed to build enough momentum from their IPOs to last the entire year. Of the stocks that went public in 2011, here were the three that have climbed the highest since their initial offerings:

1. Imperva (NYSE: IMPV)

Market Cap: $677 million

IPO Date: November 8

Gains Since: 93%

Imperva priced its IPO at $18 a share and finished the year at a high of $34.81 a share. The data security software provider raised $90 million in its initial public offering after upping its price from an expected range of $14 to $16. Shares of Imperva surged 28% in the stock’s first day of trading, and continued their upward trajectory through the final two months of the year. Imperva has never been profitable since its inception in 2002. But because its revenue grew 40% year-over-year in the first nine months of 2011, it created enough buzz to boost the stock in early trading.

2. GNC Holdings (NYSE: GNC)

Market Cap: $3.03 billion

IPO Date: April 1

Gains Since: 81%

The vitamin and nutritional supplements retailer did some heavy lifting on its first day of trading, gaining 4.7% from its IPO price of $16 a share. But GNC’s most impressive gains have occurred in the nine months since the company went public. Traditionally geared toward hard-core male bodybuilders, GNC expanded its advertising by targeting women and baby boomers. The company added 125 new U.S. stores this year, helping offset its $900 million debt load. GNC’s stock really flexed its muscles in October, going from $20.06 at the start of the month to $26.62 on November 3 – a 33% jump.

3. ServiceSource International (Nasdaq: SREV)

Market Cap: $1.07 billion

IPO Date: March 25

Gains Since: 57%

As a provider of cloud solutions that drive renewals and subscriptions for tech companies, ServiceSource is a member of one of the hottest industries going at the moment. It took advantage of the cloud service industry’s popularity by raising $119 million at $10 a share in its IPO. By generating $189 millionof revenue in 2011, ServiceSource is nearly profitable – a good sign for 2012 and beyond.

Published by Wyatt Investment Research at