This week marks an anniversary most investors would rather not celebrate. A year ago, markets entered the most tumultuous period since the depths of the financial crisis. As U.S. policy makers wrangled over the nation's debt ceiling, investors endured hair-raising plunges in stock markets. Within seven days, the U.S. had lost its triple-A credit rating from Standard & Poor's. There were dire predictions: Investors would flee U.S. Treasurys, sending the government's interest costs higher. Stocks would plummet. Looking back now, those bleak forecasts seem overblown. The flight of money from the U.S. never materialized.