From the API Developers guide, using a feed like this:

http://finance.google.com/finance/feeds/default/portfolios/1/positions?returns=true&transactions=true

should return the market value of each position, but it doesn't. The only performance data return using the "returns=true" option is the standard data of returns based on these time periods:

* One week * Four weeks * Year-to-date * One year * Three years * Five years * Overall

What I really need is the market value performance statistic for each position which as I said before, is not being returned when requesting data about each position.

Anyone else having this problem?

Here's the link to the Guide:
http://code.google.com/apis/finance/reference.html#Parameters