Sorry, I couldn't find pricing data for that day. The closing price for Microsoft (MSFT) on December 31, 1999 was $35.62. It was down 0.6% for the day. The latest price is $430.29.
DATE
OPEN
HIGH
LOW
CLOSE
VOLUME
December 31 1999
$35.85
$35.93
$35.47
$35.62
12,517,600
Daily pricing data for Microsoft dates back to 3/13/1986, and may be incomplete.