After China’s stock market experienced its second-worst day on Monday, all eyes are on Beijing, where the government faces a stark dilemma and a serious challenge to its credibility. The unprecedented intervention measures already rolled out in the past month include a ban on short selling and initial public offerings, forced purchases of shares by state-owned investors, a ban on sales by leading shareholders and direct credit support from the central bank. For three consecutive weeks, China’s benchmark index has rallied from the low it hit in early July, when the government unveiled most of these measures following a collapse of more than 30 per cent in less than a month. But after a mediocre performance for most of the day, the sell-off resumed in earnest in late Monday trading, taking the Shanghai Composite Index from a drop of about 3 per cent at 2pm to close an hour later down 8.5 per cent.