NEW YORK (TheStreet) -- Portola Pharmaceuticals (PTLA) - Get Report stock is slipping by 6.36% to $18.98 on heavy trading volume late Monday afternoon, as Goldman Sachs downgraded the stock to "neutral" from "buy."

The lower rating comes after the South San Francisco-based biopharmaceutical company released disappointing results from a phase 3 trial last week.

Portola said betrixaban, its oral treatment for blood clots, was not statistically different than the current standard of care.

"This Phase 3 pivotal study for betrixaban in acute medically ill patients at risk for blood clots was intended to support a single study regulatory filing, per the agreement with the FDA. We're concerned about the near-miss (p=0.054) for the first cohort in a hierarchical analysis plan, which in principle disallows progression to the next two levels of analysis even though those did reach stat. sig," Goldman said in an analyst note earlier today.

Additionally, the firm reduced its estimated probability of regulatory and commercial success for the drug to 20% from 60%. The lower probability of success decreases Goldman's sales projection to $130 million to $360 million in 2020.

"While we are less optimistic about the outlook for betrixaban, we recognize there may be upside to our estimates if it does get filed and approved expeditiously," the firm added.

Goldman also cut its price target on the stock to $30 from $65. 

About 4.46 million of Portola's shares were traded by this afternoon compared to its average volume of 1.3 million shares per day.

Separately, TheStreet Ratings Team has a "Sell" rating with a score of D on the stock.

This is driven by a few notable weaknesses, which should have a greater impact than any strengths, and could make it more difficult for investors to achieve positive results compared to most of stocks covered.

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

Recently, 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.

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

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