A beleaguered pharmaceutical stock is shaking off one firm's downgrade on Monday.

Shares of Mallinckrodt (MNK) , a UK-based pharmaceutical company, were rising over half a percent during mid-morning trading on Monday despite analysts at UBS lowering their rating on its stock to "Neutral" from "Buy."

The firm, however, assigned the stock a $24 price target, roughly $2 higher than Mallinckrodt's share price Monday morning.

UBS lowered its target from "Buy" based mainly on persisting overhangs from one of Mallinckrodt's essential drugs, Acthar.

Shares of Mallinckrodt were sent plummeting to all-time lows last week after the firm announced disappointing third-quarter financial results and weaker-than-expected sales of Acthar.

Sales of the drug used to treat infantile spasms and multiple sclerosis, slowed during the quarter to $309 million, a drop of 6% year-over-year.

The drug represents Mallinckrodt most significant source of profits, accounting for 42% of its overall revenue. The company said it expects further sales declines of the drug in the fourth-quarter vs. the third-quarter.

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