Beijing waded in to prop up China’s stock and currency markets on Tuesday, helping to temper losses by calming fears over the looming expiration of a share-sale ban and intervening to boost the renminbi. Some traders and analysts said the “national team” of state-owned financial institutions also resumed buying shares, despite the securities regulator’s pledge in November to halt regular purchases. The blue-chip CSI 300 index closed 0.3 higher on Tuesday after its 7 per cent fall on Monday triggered a market-wide trading halt under a new “circuit breaker” mechanism intended to interrupt panic selling. But the broader Shanghai Composite Index fell 0.3 per cent, while the Shenzhen Composite lost 1.9 per cent, adding to its 8.2 per cent tumble on Monday.