W-7 is the form for a non-citizen to get a US Tax ID number.W-8BEN is the certificate of foreign status and the form to claim treaty benefits.To have a US bank hold your stocks and receive dividends for you they are going to need the W-8BEN.If you need to file a US tax return. (For Example 1040-NR) you will need to file the W-7 to get a tax ID number.FYI: If all you are doing in the US is trading stocks as a non-resident, you should not need to file a US tax return.