What happened

Alexion Pharmaceuticals (NASDAQ:ALXN) trailed the market by a wide margin last month, shedding 21% compared to a 9% slump in the S&P 500, according to data provided by S&P Global Market Intelligence.

The decline ensured that the stock ended 2018 down 19% while the broader market lost 6%.

Check out the latest Alexion earnings call transcript.

A man and a woman wearing lab coats and protective glasses looking at a petri dish under a microscope

Image source: Getty Images.

So what

The biotech company was caught up in spiking market volatility last month, which hit riskier stocks especially hard. Shares also seemed to move in sympathy with peer Achillion Pharmaceuticals after it issued a drug testing update for a key treatment that investors panned. For its part, Alexion said earlier in the month that its newest blood disorder treatments appear to be progressing well through clinical testing phases.

Now what

Investors will get updates on these treatments, and on Alexion's latest revenue figures, when the company posts fourth-quarter results on Feb. 4. Still, the stock is likely to remain highly volatile as Wall Street reacts to any perceived changes in the commercial viability of its drug pipeline. Thus, Alexion should only be in your portfolio if you are willing to endure extreme pricing swings as you wait for a clearer drug treatment picture to emerge.