Asian markets have tumbled across the board following weakness on the Wall Street.The Hang Seng has slumped 689 points to 20,686. The Nikkei has plunged 428 points to 16,047.The Seoul Composite index has crashed 6.2% (113 points) to 1705. The Taiwan Weighted and Straits Times index are down around 3.5% each at 8293 (down 300 points) and 3153 (down 121 points), respectively.The Shanghai Composite index has shed 82 points at 4788.
