Shares of Adobe Systems (Nasdaq: ADBE) fell about 10 percent Thursday after the stock was downgraded to "neutral" by an analyst, who cited valuation concerns and a tech slowdown. Shares in the software company were down or 7.19 to 59. The stock dipped in November when another analyst downgraded the stock, citing valuation. Morgan Stanley Dean Witter analyst Rebecca Runkle downgraded shares to "neutral," from "outperform," blaming the economy and valuation rather than internal problems at the company. "Adobe trades at a (price to earnings ratio) to growth of two times, well ahead of its closest peers, such as Macromedia (Nasdaq: MACR). The slowing economy and spate of pre-releases, on the margin, make us more nervous about recommending such a high-multiple stock," Runkle said in a research note. She cited warnings from Apple (Nasdaq: APPL), Gateway (NYSE: GTW) and Compaq (NYSE: CPQ) as well as Kodak (NYSE: EK) as signs of troubled times for the graphics business.