Shares of CV Therapeutics Inc.(Nasdaq: CVTX) fell on Wednesday, after Citigroup downgraded the firm.

CV Therapeutics fell 67 cents,the or 8.42 percent, to $7.29 after the rating on stock was cut to 'sell' from 'hold.'

Citigroup analyst Dr. Yaron Werber lowered the firm's price target to $6 from $15, stating that he saw diminished market potential for Ranexa, a drug already approved to treat chronic angina. A study involving the drug this week showed that Ranexa did not meet its goals.

He also noted that the company has high operating costs and is in need of additional financing. He stated that finding the funds could be difficult based on the Ranexa results and the current amount of debt at the firm.