Pooled Funds
  
See: Pooling-of-interest. See: Family Office. See: Omnibus Account. See: Wrap Account.
When you pool your funds, you aggregate them. Like...everybody steps up to the edge of the empty swimming pool after drinking three Big Gulps and, um...contributes. Then that total pool of collected...funds...can be invested collectively.
Why would you pool funds this way? Well, it gives you more heft, volume discounts to services, better attention from the various players with whom you interact. The key friction point revolves around goals, time horizon, and abilities to take risk. If everyone's on the same page, then great. If not, then there are smaller ponds that individuals probably oughta make, and go it on their own.