AbbVie (NYSE:ABBV), a global biopharmaceutical company, is in the midst of its first disappointing year as a publicly traded company. Despite continuing to produce industry-leading growth for its bottom and top lines, the drugmaker's stock has lost nearly a quarter of its value in 2015:

ABBV Chart

This year, AbbVie's stock has gotten crushed because of lingering doubts about the company's cash flows once anti-inflammatory drug Humira loses exclusivity in the U.S. in 2017, as well as last week's revelation that its hepatitis C drugs Viekira Pak and Technivie were linked to 10 deaths in patients with advanced liver disease.

Viekira

Source: AbbVie.

Interestingly enough, though, Wall Street has remained a devout fan of AbbVie. Even after the news broke about the company's hep C drugs, for instance, analysts covering this stock barely lowered any of their forward-looking revenue or earnings projections, according to data compiled from S&P Capital IQ.

As a result, the Street's average 12-month price target for this beaten-down biotech stock remains extremely optimistic at $73 a share, meaning that analysts think AbbVie has a potential upside of 43% from current levels. Supporting this price target, the Street expects AbbVie's total revenue to grow by 15.3% and its EPS by 19% next year. 

Given this noteworthy disagreement between Wall Street and Mr. Market, let's dig deeper to see if investors should start stuffing their portfolios full of AbbVie stock or avoid it altogether.

AbbVie's problems might be far more serious than some think
To understand why the market has been trashing AbbVie's stock for the better part of the year, I think it's important to first consider the company's balance sheet. AbbVie sports a total debt-to-equity ratio of an eye-popping 568% at last count, largely because of its $21 billion buyout of Pharmacyclics. Putting this number into context, AbbVie's D/E far exceeds that of many of its closest peers:

CompanyDebt-to-Equity Ratio
AbbVie 568%
Celgene 120%
Gilead Sciences 74%

By comparison, Celgene (NASDAQ:CELG) and Gilead Sciences (NASDAQ:GILD) have both been able to keep their financial leverage from ballooning to such astronomical levels by acquiring relatively smaller companies to build out their clinical pipelines. Celgene, for instance, paid only $7.2 billion for Receptos, and Gilead hasn't made a billion dollar-plus acquisition in almost four years. 

This huge amount of financial leverage caused rating agencies such as Moody's Corp. to downgrade AbbVie's rating to Baa1, meaning that the company is viewed as a "moderate credit risk." Put it this way: If AbbVie were a person looking to take out a mortgage, that person would probably have trouble doing so -- at least at a reasonable interest rate.  

Complicating matters further, Moody's Corp. noted in its review that AbbVie needs to continue generating top-notch growth from key products such as Humira, Viekira Pak, and the newly-acquired Imbruvica -- via the Pharmacyclics acquisition -- to meet its long-term financial obligations. And that's where things start to get really iffy.

Humira's long-term revenues are obviously in question because of its looming U.S. patent expiration. After all, a few analysts have already diverged from their peers on this point, suggesting that biosimilars could devastate Humira's sales by 2018.

And Viekira Pak may never live up to its commercial potential for a variety of reasons, such as these new liver damage warnings that make it even harder to compete against Gilead's rock-star hep C drugs, a rapidly evolving hep C market that should see a handful of newer drugs with shorter treatment times in the near future, and a decline in overall demand for these drugs in most Western nations.

Yet another concern
Blood cancer drug Imbruvica's commercial potential is also a major point of contention. AbbVie's management believes that Imbruvica will eventually generate peak revenue for the company of around $7 billion per year. But there are a lot of moving parts to this estimate.

First off, Imbruvica will need to successfully migrate to earlier lines of treatment for its approved indications and expand into a variety of other B-cell malignancies to achieve this lofty sales target. The catch is that numerous companies -- most notably Celgene -- are targeting some of the same indications with a host of potent experimental-stage drugs.

There is also the distinct possibility that the growing public outcry over drug prices could spill over into the oncology space, which has been largely untouched by this debate so far. Indeed, it's worth noting that pharmacy benefits managers have just started making some potentially game-changing proposals regarding the pricing schemes for new cancer treatments or label expansions for drugs already on the market. 

Foolish bottom line
AbbVie's massive Pharmacyclics acquisition may turn out to be a huge anchor around the company's neck. If Humira, Viekira Pak, or Imbruvica miss the mark in terms of annual sales growth moving forward or its profit margins fall because of the raging drug pricing debate, the company may have to look into doing things it has never done, such as suspending share buybacks or cutting its dividend. Put simply, management took on a tremendous amount of risk by paying top dollar for Pharmacyclics, but the potential rewards now look more questionable than ever. That's why you may want to avoid AbbVie for the time being, and instead consider drugmakers with cleaner balance sheets during this period of major uncertainty for the prescription-drug industry.  

George Budwell owns shares of AbbVie, Celgene, and Gilead Sciences. The Motley Fool owns shares of and recommends Celgene and Gilead Sciences. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.