What happened

Anthem (ELV 1.11%) shareholders underperformed the market last month as their investment shed 12% compared to a roughly flat result for the S&P 500, according to data provided by S&P Global Market Intelligence.

The drop added to recent losses for investors, with shares gaining only 15% in 2019, or about half the broader market's return for the year.

A pharmacist helps a patient.

Image source: Getty Images.

So what

January's decline came following the health insurance giant's fiscal fourth-quarter report. That announcement met expectations in terms of membership growth and earnings gains. However, investors chose to focus instead on the conservative outlook that Anthem issued for the 2020 year.

Now what

CEO Gail Boudreaux and her executive team see medical membership rising to around 42 million people from 41 million in 2019, helping push revenue to $117 billion compared to $103 billion. The healthcare giant is expecting a few unusual costs, though, which should pressure earnings in 2020. While they watch for signs that this expense boost is only temporary, investors this year are bracing for volatility around the U.S. presidential election, in which the healthcare industry is likely to feature prominently for candidates proposing sweeping changes to companies' business models.