China's trade surplus isn't about trade policy. It's about sex ratios and bank loans.

Economists have long argued about why China exports so much more than it imports. This paper finds the main reasons are not trade policy, but things like an unbalanced sex ratio and how banks lend money.

For years, many governments blamed China's trade policies for its massive export surplus. This paper shows those policies play only a small role. The real drivers are deep internal issues, like how many men there are compared to women, and which companies get bank loans. This means that if trading partners want to balance trade, they need to ask China to change its social and financial systems, not just its tariffs.