No. of Recommendations: 2
The various sources for ^GSPC are in agreement (yahoo, gtr1, barchart, FRED):
yahoo ^GSPC is about 18 in 1928, and about 7500 now.
gtr1 GSPC is 13.9200 times yahoo ^GSPC, with a maximum difference of 0.0009 (over 98 years).
barchart $SPX matches yahoo ^GSPC, with a maximum difference of 0.0002 (over 2 years).
FRED SP500 price matches yahoo ^GSPC with the following maximum errors (over 10 years):
rank difference
1 5.2898
2 1.0500
3 0.1301
4 0.0400
5 0.0299
6 0.0201
7 0.0200
8 0.0101
9 0.0099
10 0.0002
gtr1 S5 is about 14.4 times yahoo ^GSPC, with a maximum difference of 43 (over 98 years), and with about a 2% standard deviation in the error term (this decreases to about 0.7% on average after 1950).
yahoo ^GSPC:
https://finance.yahoo.com/quote/%5EGSPC/history/GTR1 GSPC:
https://gtr1.net/2013/?~GSPC:h1::trp%281,1%29ne-99...barchart $SPX:
https://www.barchart.com/stocks/quotes/$...FRED SP500 price:
https://fred.stlouisfed.org/series/SP500GTR1 S5:
https://gtr1.net/2013/?~S5T:h1::trp%281,1%29ne-999... 