Charles Duncan raised his rating to "Strong Buy," his highest rating, from "Market Outperform." He said the San Diego company presented more details about a midstage trial of the drug at an industry conference Monday, and he was impressed by evidence showing the drug can lead to improvement within six weeks.

"The full data presentation confirmed top-line results that had been released in March, which showed statistically significant improvement of anti-psychotic efficacy, with the added benefits of an improved safety profile and a faster onset of action," he said.

Shares rose $1.02, or 9.1 percent, to close at $12.22 Wednesday.

Acadia is testing pimavanserin as a treatment for schizophrenia and Parkinson's disease psychosis. The biopharmaceutical company reported preliminary data from that trial in March, and shares more than doubled in a day. Acadia will host an investor meeting Friday.

Duncan kept a price target of $21 per share, and said that by early 2008, Acadia should be able to find a pharmaceutical or biotechnology company to help develop and market pimavanserin.

The analyst said there are more than 3 million schizophrenia patients in the U.S., and the top drugs in the market bring in more than $9 billion in annual revenue.