SGX NIFTY stands for Singapore Exchange Nifty. The Indian Stock market i.e. Sensex and Nifty 50 is indirectly related to the SGX Nifty along with the other Indices around the world. Another point is that both India as well as Singapore is in same continent which co-relates the whole thing. It can also be seen from "The Golden Monday" of Indian Stock Market just after the election results when both Sensex and Nifty closed on upper circuit. On the same day, SGX Nifty was up by more that 600 points. Not only this. if some steep rise/fall happens in any of the Indices around the world it affects other exchanges.
In this globalized world, where countries can trade with other countries around the globe, it is very much important to look upon other markets of the world as the first effect of economic performance comes on the stock market.
Ravi Somani, CFA