China's antitrust crackdown signals a new era of regulatory scrutiny in the country and threatens to end the days when products from Audi sedans to Starbucks lattes generate fatter profits in Beijing than in London or New York.

In the past month, Chinese antitrust authorities pressured at least seven carmakers to cut prices and raided the offices of software maker Microsoft Corp. The companies join Qualcomm Inc., Caterpillar Inc., Mead Johnson Nutrition Co., and Danone among foreign-owned businesses that have fallen under anti-monopoly scrutiny in China since last year.

The probes, combined with signs the government is shunning some U.S. technology companies for security reasons, have left foreign businesses struggling to figure out the evolving laws and regulations in the world's most populous country. Those seeking to adapt face the challenge of interpreting vague rules in an economy that's no longer as reliant on foreign investment as in past decades.