NEW YORK (TheStreet) -- Shares of Alnylam Pharmaceuticals (ALNY) were falling on heavy trading volume late Friday morning after the company discontinued the development of revusiran, one of the company's gene-silencing candidates.

The drug was meant to treat a fatal disease that can cause heart failure. But in a late-stage clinical trial of the treatment more patients died after receiving revusiran than those who were administered a placebo.

Shares of Alnylam tumbled more than 43% yesterday after the announcement.

Morgan Stanley cut its rating on the stock earlier today to "equal weight" from "overweight," the Fly reports.

The firm slashed its price target to $36 from $93 on shares of the Cambridge, MA-based biopharmaceutical company.

The stock was downgraded yesterday at JPMorgan to "neutral" from "overweight" and at Barclays to "equal weight" from "overweight."

More than 2.01 million shares of the company have traded hands so far on Friday vs. the 30-day average volume of about 1.12 million shares.

Separately, TheStreet Ratings objectively rated this stock according to its "risk-adjusted" total return prospect over a 12-month investment horizon. Not based on the news in any given day, the rating may differ from Jim Cramer's view or that of this articles's author.

TheStreet Ratings rated this stock as a "sell" with a ratings score of D.

The company's weaknesses can be seen in multiple areas, such as its deteriorating net income, disappointing return on equity, weak operating cash flow, generally disappointing historical performance in the stock itself and feeble growth in its earnings per share.

You can view the full analysis from the report here: ALNY