Why SPY and S&P 500 index differ so much?

[emk662]

Why SPY and S&P 500 index differ so much today? SPY is up 1.34 (1.04%) to 130.71, but S&P 500 index is up only 9 (0.69%) to 1305.31.

Thanks.

 

[BeatingtheSP500]

I think it's because they are measured at different times. The Friday close was 4:00 for the SPX, and 4:15 for the SPY? Therefore you will have 2 different "up" numbers. Same thing with the close today - I think it went up slightly between 4 and 4:15.