The S&P 500 is back near where it was a month ago. A surge into November has been met by recent profit-taking as we head into the Thanksgiving holidays. In pullbacks like these, I like to scan the lists of losing stocks to see if any bargains get uncovered. I found three, all of which hit 52-week lows this week, and all of which are still solid long-term plays. The pullback in these names should set the stage for a much better 2011.

NuVasive (Nasdaq: NUVA)
I recommended this stock two weeks ago as part of a paired trade play against Intuitive Surgical (Nasdaq: ISRG). [Read my analysis here ]

Since then, Intuitive Surgical has fallen roughly -10% while NuVasive has barely moved. That’s logical: in a tough trading environment, the short end of paired trades is likely to play out better than the long end. Even as Intuitive Surgical comes back down to earth, the real story here is NuVasive’s eventual upward move. It won’t come quickly — few near-term positive catalysts exist — but as 2011 unfolds, investors are likely to see that NuVasive’s recent quarterly missteps are more of a function of an unsettled health care environment than any company-specific troubles. [See our free course: Catalyst Investing Secrets]

As the dust settles, the fact that NuVasive’s technology leads to improved patient outcomes and lower total healthcare costs is likely to again be the focus of health care insurers — and investors. Shares trade for less than 20 times next year’s earnings for the first time in the company’s history  (going back to 2004). A forward multiple closer to 30 still seems justified in the context of long-term growth — that means +50% upside in 2011.

EnerNOC (Nasdaq: ENOC)
Investors love stocks that are timely, looking to buy ahead of important news or a robust quarter. That’s trouble for this clean energy play, which just reported its seasonally strongest quarter. EnerNOC earned $1.67 a share in the September quarter, offsetting about $1.20 in losses in the other three quarters of the year. And since EnerNOC’s profits won’t re-appear until next summer, investors are drifting away, pushing shares down to a 52-week low. And that spells b-a-r-g-a-i-n for long-term investors.

EnerNOC uses its Network Operating Center (NOC) to provide energy management and efficiency solutions to assist grid operators, utilities and large companies. For example, many utilities must invest in excess capacity to handle unusual demand spikes that may only happen a few times a year. By sharing the load with other utilities and working with large customers to agree to curtail usage at peak times, the utility can save a great deal of money by cutting the need for additional power plants. The International Energy Agency (IEA) refers to this as “cost avoidance,” and estimates that by deploying enhanced grid intelligence, utilities can save nearly $60 billion in the next 20 years.

Investors are also perhaps negatively focusing on the fact that growth is likely to cool from around +50% this year to around +20% next year. That’s still a respectable growth rate, and it can be maintained for quite a while to come as the company signs up new domestic customers and starts to penetrate international markets. EnerNOC recently signed its biggest contract ever with the Tennessee Valley Authority (TVA), the nation’s largest power cooperative.

As I noted when I looked at EnerNOC back in the spring  “young, high-growth companies like EnerNOC may look expensive based on near-term metrics, but can often be real bargains in the context of long-term growth.” Since then, the company has invested heavily in sales and other key areas to handle even more growth in the coming years. And with shares now -20% below where they were when I wrote about the stock in April, and -40% off of its 52-week-high, this is a second chance to get in on a high-growth business model.

Christopher & Banks (NYSE: CBK)
When a company stumbles, you have to determine whether it’s a function of fixable problems or if it’s the result of a broken business model. In the case of this retailer, shares are hitting fresh 52-week lows due to tepid consumer spending and poor decisions on the merchandising front. The company’s board has hit the reset button by installing new leadership, but this is a retailer that still has considerable brand cachet with its target demographic — middle aged-women that have relied on the retailer for many years for their professional attire. .

Just like Nuvasive and EnerNOC, Christopher & Banks isn’t poised for a quick rebound. Instead, I see catalysts coming in the first half of 2011 in two stages. First, if employment trends start to improve, so will sentiment toward these kinds of stocks. Second, new leadership will aim to bring an improved merchandising touch, and it only takes a little stirring on the same-store sales front to get investors interested in this rebound candidate. Notably, Christopher & Banks will be coming up against very easy sales comparisons as we head into next summer.

Meanwhile, more than half of the company’s $186 million market value is accounted for in cash. Back that cash out, and the company is valued at less than 20% of trailing sales. That’s less than half or even a third of the percentage of peers such as Ann Taylor (NYSE: ANN), Charming Shoppes (Nasdaq: CHRS) and Talbots (NYSE: TLB).  Turning around retail operations takes time. Christopher & Banks has had to do it before, in 1997, and 2003. This down leg of the cycle will also be met with better days ahead.

Action to Take –> Stocks hitting 52-week lows are a sign they are out of favor. And they rarely suddenly move back into favor, so these are long-term holdings that may take a while to get going again. But when they do, each of these names looks to have at least +50% upside.