ACADIA Pharmaceuticals (ACAD) had the highest return between August 1, 2019 and October 31, 2019 by a mid-cap US stock or mid-cap US stock, returning 62.6%.
Badger Meter (BMI) had the highest return between February 1, 1981 and June 30, 1987 by a US stock in the Information Technology Sector, returning 891.3%.
The closing price for the Dow Jones Industrial Average (DJI) on December 31, 2020 was $30,604.64. It was up 0.6% for the day. The latest price is $42,389.86.
Sorry, I couldn't find pricing data for that day. The closing price for the S&P 500 (GSPC) on November 3, 2000 was $1,426.69. It was down 0.1% for the day. The latest price is $5,835.47.