Business Master requires you to gain to monopolies in a single trade with any other player. Start a two player game where you control both players. Once you have enough properties between the two players, simply trade the properties.
If you need to, you can trade part of a completed monopoly to player two, simply to trade it back with another monopoly as part of a separate trade. Once the trade is complete, the trophy will unlock.
Because of its nature, this trophy can pretty easily be done alongside the "Out of Stock" trophy and the "Now We Can Play" trophy.