BANGKOK (AP) — Thailand's stock market and currency tumbled and the prime minister canceled an overseas trip Wednesday amid concerns about long-ailing King Bhumibol Adulyadej's health. Thai stocks have slid daily since Sunday, when the royal palace announced that the 88-year-old Bhumibol's condition was unstable, the first time it has used that phrase regarding the king's health. Because Bhumibol has been king since 1946, there is great concern about the eventual succession. Bhumibol, a constitutional monarch with no formal political role, is widely regarded as Thailand's unifying figure.