China is not only tightening its political grip on Hong Kong to rein in the restive city, it’s pushing harder to deepen its influence over the international finance hub's business life.

From real estate to initial public offerings, debt issuance and telecommunications, mainland Chinese companies — many of which have government backing — are playing increasingly assertive roles in almost every corner of the city. It’s a shift that has been in progress since the handover in 1997.

While supporters of greater economic integration point to the growth-boosting impact of Chinese investment in Hong Kong, critics see it as yet another reflection of the city’s diminishing autonomy from the mainland. That concern has swelled in recent weeks after China said it would impose contentious national security legislation on Hong Kong, threatening the independence of a judicial system that has been a key draw for international companies and investors.