If they do then..do they have borrowing arrangements set up, as happens with say, shares? are they using clients BTC?
I notice that on page 43 of the prospectus for
http://www.digitalbtc.com/ it says.
Digital CC trades or proposes to trade digital currencies by using specialised
strategies which include arbitrage, buying long positions, selling short positions,
futures contracts and market making at exchanges (Bitcoin exchanges are
described below).
http://www.digitalbtc.com/wp-content/uploads/sites/2/2014/03/Prospectus.pdf