https://apnews.com/5cabed0ca74d44188a9ab4587920a948 > NEW YORK (AP) — Thursday's massacre of Facebook shares, which plunged 19 percent in the biggest one-day drop in history, answers one big question. Turns out the stock can fall every bit as fast as it rises. > But others await. Is this a temporary setback for the giant social network, or the start of a painful new journey? And does it portend similar trouble for other high-flying tech giants?