Complex sentence: Such ownership is real and legally enforced, as are the profits made from it, but the capital involved is fictitious; it is "money that is thrown into circulation as capital without any material basis in commodities or productive activity".
Split into simpler sentences: Such ownership is real and legally enforced, as are the profits made from it. But the capital involved is fictitious; it is "money that is thrown into circulation as capital without any material basis in commodities or productive activity".