A default is, again, a remote possibility. But its potential impact is so huge, even that slim chance is already being reflected in markets. The yield on 10-year and 30-year U.S. Treasury bonds is already inching up, reflecting increased risk of holding them. The Dow Jones Industrial Average and bitcoin have both limped downwards over the past two weeks, though other uncertainties in the market make it hard to connect those moves directly to the debt showdown.