Sorry, I couldn't find pricing data for that day. The closing price for the S&P 500 (GSPC) on December 29, 2017 was $2,673.61. It was down 0.6% for the day. The latest price is $7,408.50.
| DATE | OPEN | HIGH | LOW | CLOSE | VOLUME |
|---|---|---|---|---|---|
December 29 2017 | $2,689.15 | $2,692.12 | $2,673.61 | $2,673.61 | 2,447,760,000 |
Daily pricing data for the S&P 500 dates back to 12/30/1927, and may be incomplete.