NEW YORK (CNNMoney.com) - Aetna's new president and chief executive, Ronald Williams, can remember a time when Wall Street wanted little to do with the troubled health insurer.

Despite being one of the largest health insurers in the country, the Hartford, Conn.-based company suffered from millions of dollars in losses, a withering stock price and declining memberships. Adding to its woes, Aetna (Research) was reputationally reviled by some members and doctors that criticized the corporate giant's billing practices as well as its interference with patient care.

But that was then. Fast forward five years and today's Aetna is a classic turnaround story.

Williams, who took the helm from former CEO John Rowe last week, is now leading a company that analysts expect to be one of the winners in 2006. In the last year alone, Aetna shares surged over 52 percent with the stock currently near its 52-week high. But despite the impressive run-up, analysts are bullish that the company has more room to grow in the wake of its strong fourth quarter earnings report last week. That's good news for investors who may have worried about missing out on the rally.

"Aetna had a lot of trouble a few years ago but a new management team came in, cut costs, let some business go and did a good job basically getting the company back on track," said Paul Newsome, health insurance analyst at A.G. Edwards. "The company has clearly gotten itself into a position where it can grow."

Newsome added that, while he doesn't expect Aetna's stock to grow as wildly as it did last year, there's plenty of opportunity for investors to make solid returns.

And for the new CEO Williams, who has been credited alongside former CEO Rowe for the company's turnaround, Aetna's success is a testament to the company's decision to put its customers first.

"At the heart of our success is our focus on the consumer," said Williams in an interview with CNNMoney.com. "It's giving us insight and strategy to meet their needs. The strategy is based on improving the quality of care and improving costs."

Williams said the company is particularly focused on building its consumer-directed health insurance products, such as health savings accounts. These tax-free accounts tied to an insurance policy with a high deductible have been steadily gaining momentum in the U.S. over the past few years as healthcare costs skyrocket and employers look to cut costs.

Aetna, which was a pioneer in the HSA market back in 2002, expects consumer-driven health insurance to become a larger part of its business in years to come. With about 500,000 members currently enrolled in these plans, consumer-directed products account for about 4 percent of the company's total business, Williams said. But he expects that figure to grow to about 25 percent in the long-term as more and more consumers opt for this plan.

Prudential analyst David Shove said in a research note that the company's strong franchises in consumer-driven health plans as well as other niche markets like college students and Medicare prescriptions should drive earnings growth over the next two years. He recently lifted his 2006 estimates for the company to $5.37 a share from $5.27 and sees Aetna posting earnings of $6.02 a share in 2007. Shove also lifted his price target on the company to $105 a share from $95.

While Williams said the company's core belief is in the need for innovation, particularly when it comes to reaching the growing number of uninsured and underinsured people in the U.S. Aetna estimates that there are about 46 million people without insurance -- a market that includes college student and part-time or hourly workers.

"We believe it's a huge market opportunity," Williams said, adding that the company is actively investing in reaching the uninsured market.

He said Aetna acquired privately-held Chickering Group in 2003 because the company focused on insuring the student population. In 2005, the company bought Strategic Resource Co. -- a benefits administrator serving part-time workers -- for $250 million and ActiveHealth Management -- a company that specializes in analyzing health data, allowing Aetna to coordinate its customer's coverage with doctors -- for $400 million.

Williams said Aetna is open to more acquisitions if companies have technologies or specialties that help Aetna to reach its target markets. But he was adamant that size isn't everything.

"Our goal isn't to be the largest," he said. "Our whole strategy is being the most preferred health plan."

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What's the outlook for insurance in 2006? Find out here.