The major sell-off in metals and energy markets that started last Friday continued in full force today. Gold futures were down as much as $150 an ounce at one point this morning, with silver losing more than $3 an ounce. That's as much as a 10 percent loss in one trading session. It was the single biggest single-day drop since 1980. Copper was down more than 2 percent and platinum was down almost 5 percent. It was not a good day to be a margin clerk. It was another one of those "risk off" days that we haven't seen since when we were really worried about Greece and the eurozone. Financial markets were not immune to the selling today. The Dow and S&P were down sharply as well. That big selling finally encompassed virtually every market,...