Biogen's (NASDAQ:BIIB) run on the stock market this year has been a roller-coaster ride, to say the least. In March, the company's shares fell off a cliff, decreasing by more than 30% in just a few days. In October, Biogen's stock went in the opposite direction, skyrocketing by 28% during the month. Volatile price movements aside, the biotech company is currently attractively valued, trading at just 10.65 times past and 9.05 times future earnings.

Is Biogen a good value play, or should investors look elsewhere?

Why Biogen's stock has been so volatile 

Biogen's two massive price movements this year -- in March and in October -- had the exact same cause, namely the company's development of aducanumab to treat Alzheimer's disease (AD). The news in March was that the company was discontinuing its efforts to send aducanumab to the U.S. Food and Drug Administration's (FDA) desk for approval. The reason behind that disappointing bit of news was the fact that aducanumab failed to prove its efficacy during a pivotal phase 3 clinical study.

A doctor with her hand on her chin, thinking about something

Image source: Getty Images.

More precisely, monthly doses of aducanumab failed to slow "cognitive and functional impairment" in AD patients. However, the company brought aducanumab back from the trash bin in October because a few more monthly doses of the drug apparently tipped the scale in a different direction. Biogen now plans on sending its potential blockbuster AD drug to the FDA's desk by early 2020. 

There is, at this point, no guarantee that aducanumab will clear the FDA hurdle, but if it does, the AD medicine could be a major growth driver for Biogen. 

More products on the way

Biogen does have other promising prospects in its pipeline. For instance, still in the AD department, the company is developing BAN2401 in collaboration with Eisai. Biogen announced positive results from a phase 2 clinical study from this candidate in July. After an 18-month study with 856 patients, BAN2401 was shown to be efficient at slowing the progress of AD.

Biogen's late-stage pipeline also includes BIIB093, a product being developed to treat hemispheric infarction (a kind of stroke). Further, Biogen's BIIB111-- which is also in phase 3 -- is being developed to treat a rare genetic disease called choroideremia.

In addition to its late-stage pipeline, Biogen boasts about two dozen other candidates in early testing phases. 

Current lineup 

Biogen's current lineup is led by Tecfidera, which treats Multiple Sclerosis (MS) and is the company's top-selling product. Biogen's MS suite contains other interesting products, including Tysabri. However, sales of its MS products are crawling as of late, leading to mediocre top-line growth. During the third quarter, Biogen's total product revenue was $2.9 billion, an unimpressive 4% year-over-year increase. Top-selling product Tecfidera only increased its sales by 3% compared to the year-ago period.

The bright spot from the company's most recent quarter was Spinraza, a treatment for spinal muscular atrophy. During the third quarter, sales of Spinraza grew by 17% year over year and by 12% sequentially. All things considered, though, Biogen's current lineup isn't particularly impressive. 

Should you buy?

Though Biogen is attractively valued, the company's future largely hinges on aducanumab, and it is far from a given that the AD medicine will be approved by the FDA. Because of this uncertainty, it is difficult to put too much hope in the company, especially as there are other biotech stocks to consider. Investors would be smart to stay on the sidelines for now.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.