One reason China is setting up its sovereign wealth fund now is that huge trade surpluses and a vast reserve of foreign exchange mean it simply has too much cash to absorb into its own economy, and capital controls keep it from investing in liquid assets like American T-bills.

FORBES: Tracking The Sovereign Funds

The issue arises because Greece used so-called collective-action clauses to force a debt exchange on the vast bulk of its bondholders.

WSJ: Greek Deal Highlights Flaws in Default Swaps

But imagine a vast electronic exchange on which literally millions of bids and offers are constantly flickering.

ECONOMIST: The future of finance | The

In the most recent ProShares filing, however, the trust notes that NYSE Arca, a trading venue of NYSE Euronext ( NYX) and the primary exchange for the vast majority of U.S.-listed ETPs, would be the venue of choice.

FORBES: ProShares Considers Listing Products with BATS

The vast majority of it, though, is worthless to us and a pretty good exchange for frequent-flier miles, better search results, a fast system to qualify for credit, finding out if our babysitter has a criminal record and ads we find more useful than annoying.

FORBES: Digging Into Data-Mining Leaves Time Journalist Feeling Reassured