Questcor Pharmaceuticals Inc.’s stock jumped today after it said it did not expect Aetna Inc.’s decision to limit coverage of its sole drug to hurt business.

Shares of Anaheim-based Questcor rose 11% in early afternoon trading to a market value of $1.8 billion.

Chief Executive Don Bailey said on a call with analysts and investors that Aetna only accounts for 5% of Questcor’s prescriptions for its H.P. Acthar Gel drug, and that the drug maker remains in discussions with the Hartford, Conn.-based insurer.

The drug maker’s shares fell 48% on Wednesday after a short seller published an Internet newsletter highlighting an Aetna policy bulletin that outlined the insurer’s opinion that Acthar, which is approved for 19 different usages, is only medically necessary for one—infantile spasms.

Acthar is primarily sold for nephrotic syndrome, a kidney disorder, and for multiple sclerosis flare-ups.