Sorry, I couldn't find pricing data for that day. The closing price for Berkshire Hathaway (BRK.B) on December 31, 2018 was $204.18. The latest price is $503.40.
DATE
OPEN
HIGH
LOW
CLOSE
VOLUME
December 31 2018
$204.23
$205.01
$201.00
$204.18
5,451,900
Daily pricing data for Berkshire Hathaway dates back to 5/9/1996, and may be incomplete.