Within key industries, the iron nexus linking Communist Party officials at the helm of major state-owned enterprises, state banks, regulatory agencies and provincial and municipal governments has kept private-sector companies — Chinese and foreign — at a disadvantage, according to Craig Allen, president of the US-China Business Council. After years of promises, China this year began loosening limits on foreign participation in its financial services industry. Regulators lifted the cap on foreign stakes in securities firms, mutual fund companies and insurers, answering repeated US demands. But Allen said more is needed. “It’s really late, and it’s much less than we bargained for” when China joined the World Trade Organization in 2001, he said.