Which one of the following pairs is not correctly matched ?

The mismatched pair is Singapore: Shcomp. “Shcomp” or SHCOMP is the ticker/name of the Shanghai Composite index, which represents mainland China’s Shanghai Stock Exchange, not Singapore. Singapore’s principal benchmark is the FTSE Straits Times Index (STI), often referenced as the FTSE Straits Times Singapore index, not SHCOMP. By contrast, Nikkei is the widely recognized Japanese index, FTSE refers to UK benchmarks, and Nasdaq is a principal U.S. electronic stock market—these three are correctly paired with Japan, UK and USA respectively (internal domain knowledge). Therefore option 2 is the incorrect match.