Sorry, I couldn't find pricing data for that day. The closing price for Alphabet Inc Class A (GOOGL) on December 31, 2018 was $51.86. It was down 1.2% for the day. The latest price is $298.92.
DATE
OPEN
HIGH
LOW
CLOSE
VOLUME
December 31 2018
$52.49
$52.75
$51.26
$51.86
33,110,080
Daily pricing data for Alphabet Inc Class A dates back to 8/19/2004, and may be incomplete.