Amgen Inc. continues to benefit from a favorable ruling by the Food and Drug Administration earlier this week. Shares in the biotech firm saw a second-straight day of gains, adding 2.3 percent after it was upgraded by two investment firms Thursday.

Shares in the struggling company have gained more than 11 percent this week but are still down about 30 percent for the year.

Merrill Lynch & Co. analyst Eric Ende upped his rating to “buy” from “neutral” late Wednesday, saying the stock was a bargain. UBS Investment Bank analyst Maged Shenouda also boosted his rating to “neutral” from “sell,” saying a cloud of uncertainty was lifted from the Thousand Oaks-based company with the FDA ruling which said the company’s best-selling anemia drugs do not need additional labels requiring lower dosages over what is currently recommended.

The FDA panel of nephrologists and cardiologists suggested Tuesday that lowering the label dosages, as some critics have called for; citing studies that show health risks associated with increased dosages, would increase the chance that patients would need transfusions and could put their health in danger.

Shares in Amgen were up $1.29 to $56.93 in afternoon trading Thursday on the Nasdaq.