When login to portal, you might have entered portal url ending with wps/portal or wps/myportal. Did you ever think about what is the difference between a url containing with wps/portal wps/myportal. Read more to know...
For the base Portal, by default, the content root is "wps/portal" for unauthenticated users and "wps/myportal" for authenticated users.
So when an unauthenticated user accesses portal url http://portalserver.com/wps/portal, the Login page displays by default and after login, portal default ladning page comes up.
And when you try to access any protected resource, like http://portalserver.com/wps/portal/MyFinancePage and since you are not authenticated, so portal will redirect you to http://portalserver.com/myportal and will show you login screen.
Now after login, you will be redirected to MyFinancePage instead of portal default landing page because you have a made an attempt to access protected resource MyFinancePage.