Out of the Gate: Riverbed Technology

Shares fell $12.10, or 25.1 percent, to $35.93.

CIBC analyst Ittai Kidron was glum on the stock, saying that third-quarter results and fourth-quarter guidance wasn't "good enough" for a company "with a track record of beating expectations."

He maintained his "Sector Performer" or "Hold" rating.

Competition also should pose a significant threat as Cisco Systems Inc. and Juniper Networks Inc. release similar products, he said.

"We believe investors should still sit on the sideline until the picture becomes clearer with respect to the competitive pressures," Kidron said in a client note.

Deutsche Bank analyst Cobb Sandler, however, maintained his "Buy" rating and $70 price target, saying in a client note that Riverbed is "a clear leader" with product lines that should add to growth in coming periods.

Riverbed's latest products -- RIOS 4.1, a data security platform, and Steelhead Mobile, a disaster recovery application -- should "ramp up" 2008 sales, Sandler said.

He warned that risks to growth include too few products, rising intellectual property theft and a potential for increased competition.