Biogen's stock could fall as much as 10% once it releases new data this week on its Alzheimer's drug, aducanumab, Baird biotech analyst Brian Skorney told CNBC on Monday.

The stock could fall even further from its Monday per-share price of around $292 to about $230 if investors believe its drug will be rejected by the Food and Drug Administration, Skorney said on CNBC's "Power Lunch."

Shares of Biogen were down more than 2% in intraday trading Monday after Skorney wrote in a note to investors that he is skeptical Biogen's Alzheimer's drug will be approved by federal regulators.

"The bottom line is, the FDA standard of approval is substantial evidence of efficacy and the cumulative data for aducanumab falls really far short of this standard," he said in the note dated Dec. 2.

In March, Biogen pulled the plug on its Alzheimer's drug and sent its stock tanking after an analysis from an independent audit revealed the experimental medicine was unlikely to work. However, shares of the Cambridge, Massachusetts-based company soared on Oct. 22 after the drugmaker shocked investors by announcing it was seeking regulatory approval for the drug.

Biogen's drug targets a compound in the brain known as beta-amyloid, which is thought to play a role in the devastating disease by eroding synapses between nerve cells.

Biogen said that a new analysis of a larger dataset showed that aducanumab "reduced clinical decline in patients with early Alzheimer's disease" and patients who received the drug "experienced significant benefits on measures of cognition and function such as memory, orientation, and language."

Biogen is expected to release new data for its drug at the Clinical Trials on Alzheimer's Disease annual congress on Thursday.

Skorney said Monday that he is "calling [Biogen's] bluff."

"We do not think that data validates anything near receiving approval from the FDA," he said.

Biogen had no comment.