Having big backers usually represents a vote of confidence—but for the Postal Savings Bank of China, it signals market concerns. The bank’s shares start trading today after it raised nearly $7.4 billion with the world’s biggest IPO in two years. But nearly 80% came from “cornerstone investors”, a record level for a large share sale in Hong Kong. Companies need cornerstones when ordinary investors are not tempted: they pledge to buy shares, regardless of price, and cannot sell them for half a year. The cornerstones for Postal Savings Bank are all other Chinese state-owned companies, including a shipbuilder. The postal bank has impressive heft, boasting 500m retail customers, or more than one in three citizens. But the government insisted that the bank price its shares at a roughly 20% premium to other Chinese banks, despite rising bad loans and slowing growth. Clearly, that was a tough sell.