NEW YORK (AP) — After six days of being pounded by a virus-induced, global sell-off, U.S. markets hit a milestone this week. The S&P 500 has dropped more than 10% from the record highs set just over a week ago as a fast-spreading new virus raises the specter of damaged economies and tumbling sales for companies in the U.S., Asia, Europe and elsewhere. The S&P just went through a correction. While that can be scary, particularly when a sell-off happens as fast as it did this week, corrections are fairly regular occurrences in the stock market.