Aetna Inc., the largest U.S. health insurer, on Wednesday posted its third straight quarterly operating loss, as it struggled to leave underperforming markets behind and cope with high medical costs.

Aetna reported an operating loss of $62.4 million, or 44 cents per share, compared with $42.3 million, or 30 cents per share, a year ago. Including a $13.1 million gain from the sale of Aetna's New Jersey Medicaid membership, the firm posted a loss of 34 cents per share in the 2001 period.

Analysts had generally expected Aetna to post a loss of 55 cents per share, forecasting losses per share ranging from 12 cents to 74 cents, according to research firm Thomson Financial/First Call.

Including one-time items, Aetna posted a net loss of $54.4 million, or 38 cents per share.

Aetna's third-quarter shortfall follows operating losses of $95.9 million in the second quarter and $36.6 million in the first quarter as the 148-year-old company labors with dozens of problems stemming from a legacy of rapid expansion and underpriced insurance plans.

``We continue to experience high medical costs, which are causing us to fall far short of our ultimate goals,'' Aetna Chairman, President and CEO John Rowe said. He added that results improved from the second quarter due in part to ``a more favorable health care performance.''

``These improvements reflect the early benefits of operational changes that we have made, although we still are in the early phases of our turnaround effort,'' Rowe said. He added he does not expect major benefits from most of the strategic and operational changes until 2002 and 2003.

Revenues at Hartford, Connecticut-based Aetna fell to $6.2 billion for the quarter from $6.7 billion. The company's HMO medical cost ratio, the percentage of its premiums spent on medical expenses, fell to 90.1 percent from 91.3 percent in the second quarter of this year.

The medical cost ratio is a key indicator of profitability that measures the percentage of revenues spent on medical expenses such as payments to doctors, hospitals and for prescriptions.

Aetna shares closed Tuesday at $32.01, at the high end of its range of $23.01 to $32.10 over the last several months. The stock has gained 14 percent in just the past three days.

Aetna has been struggling with a new business strategy following ING Groep NV's acquisition last year of its profitable financial services and international arm. ING spun off the health care unit, which retained the Aetna name.

A new management team has implemented a major restructuring, with a focus on growth among mid-sized businesses while retaining larger corporate accounts.

The insurer has said its restructuring and other efforts would not improve results until 2002.

Total health membership was 17.5 million, a decrease of about 566,000 from the second quarter and 1.8 million from year-end 2000, primarily reflecting planned reductions of membership.