Google has quietly posted in the Google Web Search Help forums that they are deprecating the portfolios section in Google Finance. It is going away next month, as part of a redesign of Google Finance.

Andy from the Google Finance team wrote:

Google wrote in their help section:

In an ongoing effort to make Google Finance more accessible and user-friendly for a wider audience, we’re making a few changes to the service in November 2017.

As part of this updated experience, you’ll still be able to:

Follow the stocks you’re interested in – the list of stocks in your portfolio will be migrated into the new experience on Google automatically
Receive the latest industry news and market trends
However, as part of this updated experience, the Portfolios feature will no longer be available. To keep a copy for your records, download your portfolio now.

To give you time to download and consider alternative services, this change won’t happen until mid-November 2017.

Forum discussion at Google Web Search Help.