why is stock price data always 1 day off?
The previous day close proce reported on the 1 month chart is off by one day. Consistently.
Jason Steadele commented
S&P 500 ^GSPY shows data that is one day different than the actual market close data. For instance, If you look at https://finance.yahoo.com/quote/^GSPC/chart, and go to 10/15/2019, you will see todays closing market data, but today is 10/16/2019. Follow it back and every single date is off by one day
Now go to https://www.barchart.com/stocks/quotes/$SPX/interactive-chart and notice the difference