Shares of Biogen Idec Inc. (BIIB), the third largest biotech in the U.S., are trading lower this morning after the company said that the Food and Drug Administration has extended the review timeframe for Biogen’s New Drug Application for its multiple sclerosis drug, BG-12, by three months.

The regulatory agency didn’t request any additional studies; it just needs more time to review the application, according to the Weston, Massachusetts-based company. The three-month extension is a standard extension period.

Last week, the drug maker reported that new data for clinical trials supported the safety and efficacy of the oral drug candidate in people suffering from relapsing-remitting multiple sclerosis, or RRMS.

High expectations for BG-12, also called dimethyl fumarate, have aided in driving shares of Biogen to all-time highs in recent months as the oral therapeutic could provide an alternative to injectibles that are used as a standard of care today in treating RMMS. It is expected that the new drug would be taken twice daily.

RRMS is a chronic disease and common form of multiple sclerosis characterized by people experiencing attacks of worsening neurologic function followed by remission periods in which partial or complete recovery occurs.

Analysts have been mixed on Biogen lately given the high share value. Jefferies Group on Wednesday reiterated their “Buy” rating with a $176 per share price target. Credit Suisse has an “Outperform” rating and recently raised their price target to $175 per share from $165 per share. On the lower side of things, Zacks last week downgraded BIIB from “Outperform” to “Neutral” with a $159 price target. RBC Capital held it “Outperform” rating with a $150 per share target earlier this month.

Shares closed trading on Wednesday at $153.78 and have surged about 50 percent in the last year.