Biogen shares declined Thursday after Morgan Stanley’s Matthew Harrison downgraded them to equal weight.

“This is not a downside call, but a timing call as we see BIIB trading with the group after appreciating post the BIVV spin and on Spinraza excitement,” wrote Harrison, who lowered his 12-month price target on the stock to $305. The stock closed Wednesday at $292.64. On Thursday morning, it was down 3.75 percent.