This article explains why Yahoo! changed the look of the Portfolios page, and the options for moving back to the classic look.

It will also be helpful to explain why you cannot return or go back to the classic view of Yahoo! Finance portfolio.

Whenever we introduce a new design or feature, it's always with the goal of improving the overall experience for all users. With the recent improvements to Yahoo! Finance portfolios, we wanted to introduce an attractive and intuitive design that would be more easy to use. In addition to changing the portfolio pages themselves, we've added opportunities for users to create and edit portfolios from various Yahoo! Finance pages.

While we recognize that there are some differences in functionality with this new version, we hope you'll give it a try -- and certainly feel free to contact us with feedback. Unfortunately, we can't offer the option for users to switch back to the previous version.