Seoul shares plummeted nearly 5 percent Tuesday as technology stocks extended losses after Samsung Electronics Co. released its preliminary second-quarter earnings estimate. The Korean won fell against the US dollar. After opening 1.6 percent lower, the benchmark Korea Composite Stock Price Index extended losses, falling 395.02 points, or 4.91 percent, to close at 7,656.31. Trade volume was heavy at 512.29 million shares worth 39.66 trillion won ($25.9 billion), with decliners outnumbering gaine