Sorry, available market cap data for Exxon Mobil (XOM) starts on July 1, 1985. Exxon Mobil (XOM) has a market capitalization of $494.3B, based on 4.22B shares at a price of $117.22 (up 1.7% yesterday).

DATE	OPEN	HIGH	LOW	CLOSE	VOLUME
December 31 1980	$1.98	$2.00	$1.97	$1.98	1,662,400
December 30 1980	$1.97	$1.99	$1.97	$1.98	1,147,200
December 29 1980	$1.98	$1.98	$1.97	$1.97	1,313,600
December 26 1980	$1.97	$1.98	$1.96	$1.98	1,670,400
December 24 1980	$1.97	$1.97	$1.96	$1.97	1,638,400
December 23 1980	$2.00	$2.01	$1.96	$1.97	4,457,600
December 22 1980	$2.02	$2.02	$1.99	$2.00	3,518,400
December 19 1980	$2.04	$2.04	$2.01	$2.02	7,188,800
December 18 1980	$2.07	$2.10	$2.04	$2.04	5,790,400
December 17 1980	$2.02	$2.07	$2.02	$2.07	3,816,000
December 16 1980	$1.94	$2.01	$1.94	$2.00	4,040,000
December 15 1980	$1.93	$1.96	$1.93	$1.94	2,446,400
December 12 1980	$1.91	$1.94	$1.91	$1.93	4,892,800
December 11 1980	$1.95	$1.95	$1.89	$1.90	6,622,400
December 10 1980	$1.95	$1.98	$1.94	$1.95	6,464,000
December 09 1980	$1.92	$1.96	$1.91	$1.95	4,328,000
December 08 1980	$1.95	$1.95	$1.92	$1.92	6,112,000
December 05 1980	$2.00	$2.00	$1.96	$1.96	4,800,000
December 04 1980	$2.06	$2.06	$2.02	$2.02	3,744,000
December 03 1980	$2.07	$2.08	$2.05	$2.06	2,126,400
December 02 1980	$2.11	$2.11	$2.05	$2.07	3,598,400
December 01 1980	$2.15	$2.15	$2.10	$2.11	2,241,600
November 28 1980	$2.13	$2.17	$2.13	$2.15	2,132,800
November 26 1980	$2.11	$2.14	$2.11	$2.13	4,089,600
November 25 1980	$2.12	$2.13	$2.07	$2.10	4,553,600