Breaking the trend was the third-largest U.S. health insurer, Aetna ( AET ), which not only topped analysts' estimates when it reported fourth quarter results but also gave a 2011 view that was well above Wall Street average forecast. Aetna's profit climbed 30% to $215.6 million, even as revenue was down 2% to $8.54 billion, partly due to "lower utilization." If these results are any indication, other health insurers such as Humana ( HUM ) will report similarly healthy profits and present similarly cautious outlooks for 2011, as they move to meet the new law's minimum medical-spending requirement and as demand for medical services returns to normal levels. But judging from the stocks' outperformance year-to-date, perhaps investors believe the five could earn higher profits on possible higher enrollment and higher premiums.