HONG KONG — As American investors pull funds out of China, local financiers are focusing more on finding business domestically — and learning a homegrown card game that might help them. 

Guandan, also known as “throwing eggs” in Chinese, is a poker-like card game that originated in Jiangsu, one of the wealthiest provinces in China. Amid some of the tensest U.S.-China relations in decades, it has eclipsed Texas Hold’em as the must-have social skill for Chinese financial…