The Agricultural Bank of China’s initial public offering, expected to become the world’s largest, debuted Friday, landing squarely in the middle of a debate over whether leading Wall Street law firms should build local practice capability in Hong Kong.

The IPO on the Hong Kong and Shanghai exchanges would seem an obvious rallying cry for those arguing that top American capital markets firms will miss out on deals without their own Hong Kong lawyers — except that the lead lawyers on the AgBank deal are from New York’s Davis Polk & Wardwell, which only practices U.S. law.