It’s a “bad time to buy” Adobe (ADBE) shares, Cowen’s Walter Pritchard warned investors in a research note this morning.

Prirchard notes that the stock is traded at a “meaningful premium” to peers, at 1.35x the average valuation of large-cap software stocks. He says a key driver for the company will be adoption of Creative Suite 4, but that “visibility into this cycle should be lower than in CS3 due to strong prior upgrade cycle as well as macro uncertainty.”

Pritchard says there is a high correlation between Adobe’s sales of Creative Suite and metrics such as nominal GDP, magazine advertising, direct mail and total ad spending. He’s not predicting a decline in Adobe’s revenue - which is what happened in 2001-2002 - but he says the company is “more exposed than most investors realize” to the softening economy.

Also, Pritchard says he tested the “popular notion” of buying Adobe shares six months before a new release of Creative Suite. He says the stock actually tends to be flat for the six months before release, and then to trade down after.

Pritchard maintains a Neutral rating on the stock.

ADBE today is down 62 cents, or 1.4%, to $45.27.