Health insurer Humana on Wednesday reported lower-than expected medical costs in the first quarter, allaying investor concerns about the sector after bellwether UnitedHealth's disappointing financial results earlier this month.

Humana reported $1.2 billion in first quarter net income as the company gets better control of medical cost trends in its Medicare Advantage plans.

Key Takeaways Humana beat first-quarter profit and sales estimates as it reduced costs and exited some Medicare Advantage plans.The insurer posted a membership decline, which is said was mostly because it pulled out of what it called "unprofitable" Medicare Advantage plans and counties.