For now, the bond king Bill Gross doesn't see the sovereign debt crisis as being on the same magnitude as the subprime crisis, but he thinks a similar dynamic is at play.

On CNBC yesterday he said: "First of all, we had private credit expansion that imploded and almost exploded with the subprime and Lehman crisis... and now we’ve had public re-expansion to the extent that we’ve expanded in stocks at certain price earnings ratios, and high yield bonds at certain narrow yield spreads. That expansion is over and what we’re seeing today the hedge funds taking some of the leverage off the table.”

As for the question of magnitude, in a way it's not about the size of the defaults. Subprime loans were never that big. Lehman wasn't that big. Greece and Portugal aren't huge countries. But it's about nervousness and contagion. Who owns what, and what will they sell to raise cash?