When do "inverse" ETFs cover their shorts?

[Stephen Tashi]

Exchange traded funds like TZA and RWM attempt to get results that are the "inverse" of certain stock indexes. I understand they do this by shorting stocks. When do they cover their shorts? -before the end of each trading day?

 

[BWV]

Exchange traded funds like TZA and RWM attempt to get results that are the "inverse" of certain stock indexes. I understand they do this by shorting stocks. When do they cover their shorts? -before the end of each trading day?

At the end of the day, and they actually do not sell anything short. They utilize futures or swap contracts and settle at the end of the day (which is a primary reason why they are such crappy investments)