Google Finance fails to gather any momentum yet against Yahoo.  The comment I found useful here is the stickiness of Yahoo Finance, based on the time taken to set up preferences, making a shift to another portal a lot of work.

Google Finance Struggles for Users – –
Tancer said the key reason Google Finance is lagging behind its competitors is that personal finance Web sites like Yahoo Finance are sticky. “They allow users to personalize their stock and news preferences,” he said. “It is hard for users to enter all the information again, and that is going to be the impediment to growing in the personal finance category. It is more difficult to gain share in the personal finance category than in other Web site categories.