THE Australian stock market suffered its biggest one-day fall in over five years on Wednesday as global markets went into meltdown. Analysts said the fall was the correction "we had to have", with a downturn likely to reach an overall fall of 15 per cent for the Australian share market. Since last Monday, Australian stocks have declined 6 per cent. The global share slump was set off by a sell off in China, where the Shanghai Composite index lost nine per cent.