WellPoint Inc., the second-biggest U.S. health insurer, is still considering former Amerigroup Corp. CEO James Carlson among several finalists to become CEO, according to a person familiar with the matter.

WellPoint has delayed defining a role for Carlson, who joined WellPoint through its $4.9 billion acquisition of Amerigroup late last year, because he is a contender for the top position, said the person, who asked for anonymity because the information is private. Retired Aetna Inc. CEO Ronald Williams is also thought to be a leading candidate, according to analysts at BMO Capital Markets and Sanford C. Bernstein & Co.

Carlson, 60, built Amerigroup into one of the biggest insurers focused on the growing Medicaid sector and would bring much-needed strategic experience to the carrier. The previous CEO Angela Braly, an attorney, left last August amid complaints about disappointing profits and management missteps.

He’d be a “very solid” pick, said Mark Giambrone, a portfolio manager at Dallas-based Barrow, Hanley, Mewhinney & Strauss, WellPoint’s second-biggest stockholder. “Of the people out there as candidates, he’s certainly one I’d consider a good choice.”

Statements and filings this month have fueled speculation among analysts and shareholders that Carlson has vaulted ahead of other prospects. While Carlson joined WellPoint last month after the Amerigroup deal closed, the Indianapolis-based insurer has yet to announce his compensation package, suggesting that something bigger may be under negotiation. WellPoint also conspicuously didn’t define Carlson’s role during an investor conference last week, said Dave Shove, a BMO Capital Markets analyst in New York.

“It’s another tea leaf pointing in his direction,” Shove said.

Still, the insurer hasn’t disclosed publicly who it’s talking to and there’s no guarantee Carlson will be the choice, Shove said.

In an e-mail, Kristin Binns, a WellPoint spokeswoman, said the company wouldn’t comment on the CEO search. Maureen McDonnell, an Amerigroup spokeswoman, also declined to discuss the process or Carlson’s role. Katherine Mentus, a spokesman for Williams, declined to comment when reached by telephone.

A decision seems likely by Feb. 28, when WellPoint will hold a day-long conference for analysts, said Ana Gupte, a Sanford C. Bernstein analyst in New York. Based on conversations with investors, Williams and Carlson were “definitely the front-runners,” she said.

“People just want closure and somebody who’s going to take the reins at this point,” Gupte said. “It’s going to be a positive catalyst either way.”

WellPoint fshares were down 36 cents at midday, to $62.08 each. The shares were down 13 percent in the 12 months through Monday. The top medical insurer, Minnetonka, Minn.-based UnitedHealth Group Inc., gained 1.3 percent in that time.

WellPoint’s board has been interviewing executives and expects to make a decision by this quarter, interim CEO John Cannon told investors at a conference Jan. 8. He declined to discuss specific names. The company hired London-based recruiting firm Spencer Stuart & Associates Ltd. in September and said the process would take three to six months.

WellPoint would be a far bigger assignment for Carlson than Amerigroup, which oversaw coverage to 2.7 million people in Medicaid, the joint state-federal program for the poor. At WellPoint, he’d lead an insurance heavyweight with 36 million customers across commercial and government-backed health plans, along with dental and vision services.

Nonetheless, he’d bring a reputation for strong execution and transparency that investors found lacking under Braly, said Brian Wright, a Monness Crespi Hardt & Co. analyst.

At Amerigroup, “he was either the No. 2 or the No. 1 during a tremendous period of growth for the organization,” the analyst said.

Carlson became CEO at Amerigroup in September 2007, after four years as chief operating officer. He sold the business to WellPoint at a 43-percent premium and also is a former executive at UnitedHealth.

Williams, 63, retired in 2011 after a decade at Aetna, the nation’s third-biggest insurer, including four years as CEO and chairman. He’s credited with steering the Hartford, Conn.-based company back toward profitability, though with a stock that lagged peers during his time. He previously worked at WellPoint, running its large-employer division and a Blue Cross plan in California.

Williams’ has a non-compete agreement with Aetna that expires next month, so an extended search might suggest his chances at winning the WellPoint spot are improving, Gupte said.

Talk about Carlson has grown because WellPoint has yet to announce his stock compensation package, as it did earlier this month for another Amerigroup executive joining the company, said Wright, of Monness Crespi. “The thought process is that there could be a reason why it’s more complicated to negotiate the Carlson grant, the CEO transition,” Wright said.

Speculation heightened last week when Cannon, the interim CEO, spoke at JPMorgan Chase & Co.’s annual health-care conference in San Francisco. While Carlson has been expected to run WellPoint’s Medicaid business, Cannon said the unit would be led by Richard Zoretic, former chief operating officer at Amerigroup.

The comments are “inviting reasonable speculation about whether this means Carlson will be the next CEO,” Carl McDonald, a Citigroup analyst, wrote in a Jan. 12 research note to clients. Cannon isn’t interested in the job on a permanent basis, WellPoint has said in past statements.

Braly, appointed CEO in 2007, was ousted after investors publicly criticized her management. She resigned on Aug. 28, a month after the company missed analysts’ profit estimates for the second time in three quarters. It was the latest in a series of missteps during a tenure marked by difficulties with predicting medical costs and declining enrollment.

“I don’t think it’s rocket science,” Giambrone said about WellPoint’s leadership. “They have a great brand. They’re a low-cost producer. The company generates tremendous free-cash flow. All they have to do is operate correctly and allocate capital correctly and they have a great business. But when it’s not operated correctly, you are where you are now.”