The downgrade comes as Ciphergen shares continue to slide after the company reported lackluster sales during the second quarter.
The downgrade is the second in as many months to hit Ciphergen: Piper Jaffray on July 1 downgraded the stock to 'underperform' from 'outperform.'
Shares in the Fremont, Calif.-based protein chip company were trading down 15.5 percent, or $.49, at $2.87 on the Nasdaq exchange late this morning. The shares closed at $4.10 on July 30. Ciphergen issued its second-quarter earnings after the market closed that day.