Yahoo Inc.'s shares were down 19.17 percent at the close of Tuesday after the company announced it would be delaying the launch of its new advertising platform, Project Panama.

Yahoo Chief Executive Officer Terry Semel said the company plans to launch Project Panama in the final quarter of 2006. Yahoo says it wants to collect feedback from advertisers before shifting to the new ad platform. Semel says that he does not expect Project Panama to affect the company financially until 2007.

"Despite the delay in the upgrade of its search advertising platform, and declining search market share, we expect Yahoo to benefit from the secular growth trend in online advertising, driven by its dominant position in graphical advertising," Cowen Research Analyst Jim Friedland said in a note to Yahoo investors.

Analysts Piper Jaffray & Co said that "weak search, lack of upside, compounded by announced delay in Panama" contributed to the decline of Yahoo shares but that Yahoo's "core advertising remains strong."