Sorry, available market cap data for Berkshire Hathaway (BRK.A) starts on January 4, 1988. Berkshire Hathaway (BRK.A) has a market capitalization of $1.1T, based on 1.44M shares at a price of $734,180 (down 1.4% on Friday).

DATE	OPEN	HIGH	LOW	CLOSE	VOLUME
December 31 1984	$1,275.00	$1,300.00	$1,275.00	$1,275.00	100
December 28 1984	$1,270.00	$1,300.00	$1,270.00	$1,270.00	100
December 27 1984	$1,270.00	$1,300.00	$1,270.00	$1,270.00	80
December 26 1984	$1,270.00	$1,300.00	$1,270.00	$1,270.00	60
December 24 1984	$1,270.00	$1,295.00	$1,270.00	$1,270.00	500
December 21 1984	$1,265.00	$1,295.00	$1,265.00	$1,265.00	40
December 20 1984	$1,265.00	$1,295.00	$1,265.00	$1,265.00	200
December 19 1984	$1,265.00	$1,290.00	$1,265.00	$1,265.00	200
December 18 1984	$1,265.00	$1,290.00	$1,265.00	$1,265.00	300
December 17 1984	$1,265.00	$1,290.00	$1,265.00	$1,265.00	200
December 14 1984	$1,265.00	$1,290.00	$1,265.00	$1,265.00	300
December 13 1984	$1,265.00	$1,285.00	$1,265.00	$1,265.00	10
December 11 1984	$1,265.00	$1,290.00	$1,265.00	$1,265.00	200
December 10 1984	$1,265.00	$1,290.00	$1,265.00	$1,265.00	100
December 06 1984	$1,275.00	$1,300.00	$1,275.00	$1,275.00	40
December 05 1984	$1,275.00	$1,305.00	$1,275.00	$1,275.00	80
December 04 1984	$1,280.00	$1,305.00	$1,280.00	$1,280.00	70
December 03 1984	$1,280.00	$1,305.00	$1,280.00	$1,280.00	200
November 30 1984	$1,280.00	$1,305.00	$1,280.00	$1,280.00	100
November 29 1984	$1,290.00	$1,320.00	$1,290.00	$1,290.00	400
November 28 1984	$1,300.00	$1,320.00	$1,300.00	$1,300.00	100
November 27 1984	$1,300.00	$1,320.00	$1,300.00	$1,300.00	60
November 26 1984	$1,300.00	$1,320.00	$1,300.00	$1,300.00	80
November 23 1984	$1,300.00	$1,320.00	$1,300.00	$1,300.00	300
November 21 1984	$1,295.00	$1,320.00	$1,295.00	$1,295.00	200