A surge of cash from mainland China into Hong Kong stocks has mostly found its way into companies little known to global investors, a development already starting to alter the city’s market.

Mainland investors have plowed a net 26.4 billion yuan ($4.25 billion) into stocks traded in the former British colony since Wednesday, sending shares of Hong Kong-listed Chinese companies skyrocketing and the city's share trading volumes to record highs. But blue chip perennials, names such as HSBC Holdings, CK Hutchison Holdings. and Swire Pacific, weren't among the 10 most traded by mainland investors.