to collect in a mass

» Warren Buffet: America's Growing Trade Deficit Is Selling The Nation Out From Under Us.

He starts off with a story about Thriftville (other countries) and Squanderville (the US), with Thriftville buying up Squanderville’s bonds (debt): 

“Over time Thriftville accumulates an enormous amount of these bonds, which at their core represent claim checks on the future output of Squanderville. A few pundits in Squanderville smell trouble coming. They foresee that for the Squanders both to eat and to pay off—or simply service—the debt they’re piling up will eventually require them to work more than eight hours a day. But the residents of Squanderville are in no mood to listen to such doomsaying. 

Meanwhile, the citizens of Thriftville begin to get nervous. Just how good, they ask, are the IOUs of a shiftless island? So the Thrifts change strategy: Though they continue to hold some bonds, they sell most of them to Squanderville residents for Squanderbucks and use the proceeds to buy Squanderville land. And eventually the Thrifts own all of Squanderville… In effect, Squanderville has been colonized by purchase rather than conquest.”

If Warren Buffet’s estimates from 2003 have held true, then other countries now own around 9% of the US’s wealth.