Furthermore, there is a possibility of a shutdown of US government agencies, and US long-term bonds are firm.

The possibility of a government shutdown due to the US budget running out (by September 30th) has been increasing. A spending bill must be passed by the end of September, but the conservative hardliners of the Republican Party, the Freedom Caucus, are demanding less spending than during the Biden-McCarthy agreement in May, making an agreement difficult.

Given the high possibility of a government shutdown, short selling of US treasury bonds is not possible. This can be confirmed by past examples. During the government shutdowns in 1995-96 and 2018-19, confrontations over the budget stimulated demand for safe assets, causing US bond prices to rise. It is unlikely that US long-term interest rates will rise (price will fall) in September.