Capital Fund Management, an early practitioner of systematic-trading strategies, is re-opening a managed-futures fund that’s been off-limits to new investors since at least 2015.The Paris firm seeks to raise an additional $1 billion for the vehicle, dubbed Discus, which currently has $2.1 billion under management. With a track record that dates to 1991, Discus was among the first futures-trading programs in Europe to employ trend-following...