Stocks sunk at the open today, as traders demanded and got higher yields on government debt. The Dow tumbled 73% points, while the Nasdaq fell 1%, the S&P dropped 0.8%, and commodities retreated. The yield on 10-year Treasury notes, by contrast, moved up to 3.85%. Apple, meanwhile, declined 1.7% as investors watched to see if Steve Jobs would appear at its development conference. (More stock market stories.)