For example, Profunds prices into UJPIX how the US does at the end of the day. If the Nikkei goes up big and the US goes up bigger, you will make more than what the Nikkei will pay out (in a general sense). If the Nikkei is flat and the US goes up big, UJPIX will be up close to what the US did. If the Nikkei is down and the US goes down bigger, it will lose more than the US. The US "amplifies" what ever move Japan makes if the US move is stronger.
Jan 4 - We have transitioned into a bear market. Completely different rules apply.
May 23 - IMO, any price at/above this close makes a great Nasdaq/SP500 short.