HSBC has a strange multi-page experience, that’s not really multi page. The Login URL is https://www.security.us.hsbc.com/gsa/SECURITY_LOGON_PAGE/
You can see basically how it works from the page source.
There are three forms. The first has an ID called usernameForm. The second passwordForm. Those are for the username and password, respectively (along with birthday as an unnecessary secondary piece of information they require). The third form is to use a one-time code. I’m not using that, so ignore that for now.