Throughout history, financial markets have struggled with the issue of borders. Borders create friction, add cost and cause headaches for anyone who wants to spend money across them. On top of that, various national currencies can be wildly unstable. Could a borderless, global currency ease...

For much of this year, the S&P 500 has marched steadily higher while measures of stock market volatility, like the VIX, have stayed pretty low. But looking at the headline index only tells you part of the story. Beneath the surface of the S&P 500, individual stocks have been moving up and...