Shares of Humana (HUM) - Get Report  were down slightly Monday following an analyst upgrade that cited strong financials and growth in the health insurance giant's Medicare Advantage business.

Humana's stock price slipped to $297.66 after Cantor Fitzgerald boost its outlook on the big insurer's stock to overweight from neutral.

Analyst Steven Halper cited Humana's "strong second-quarter results" as well "growth in its Medicare Advantage business and effective cost management," according to published reports.

The Cantor Fitzgerald analyst also cited Humana's recent win in landing a Medicaid contract in Louisiana as a positive sign of that the insurer is also growing revenues beyond its Medicare Advantage business.

Humana's larger strategic investments in "population health management" and the "social determinants of health" will also boost growth over the long-term, Halper noted.

Humana boosted its guidance on membership growth to 500,000 members in 2019, up from its previous estimate of 480,000, when it released its second quarter earnings report at the end of June.

Bruce Broussard, Humana's president and CEO, told analysts in an earnings conference call that the aging population in the United States combined with "increased penetration of Medicare Advantage as a percentage of total Medicare eligible" gives the company "confidence in our long-term membership growth prospects."