Asian stock markets saw a massive decline on Friday, with as much as $750 billion being wiped out, according to Bull Theory. South Korea's KOSPI fell by 6.9%, wiping out $345 billion; Taiwan's market saw a 4% decline, erasing $198 billion; Japan's NIKKEI fell 2.4%, wiping $206 billion. The South Korean won also fell to its lowest level since 2009.