For the 2013 year end data, Diamond provided the top 1,000 comics and the top 1,000 trade lists plus a few items in both categories from smaller publishers which fell under the top 1,000 lists. Neither the top 1,000 comics nor the top 1,000 trades lists included index values for the items. I took the total known sales for each issue over the year and used that to calculate the minimum number of estimated units each item on the list sold. As a result, the list stair steps in an odd manner which reflects the data that was and wasn't available from the monthly lists. This year end data is more of a ballpark of how the items sold versus the usual monthly estimates based on the order index for each item.
Marvel had 498 of the items list of the top 1,000 comics for 2013 with DC taking another 410 of the slots on the list. Image was a distant third with 49 items followed by Dark Horse with 18 items and IDW Publishing with 15 items. The remaining ten items in the top 1,000 were split across Aspen with 5, Boom! Studios with 2, and Archie Comics, Dynamite Entertainment and Valiant with each of those publisher only landing a single item on the list. On the trades list, DC took 362 of the top 1,000 slots with Marvel a distant second 288 items on the list. Image had 96 items on the list, Dark Horse placed 91 items and IDW another 42. The remaining items were split across another 26 publishers.
Though the numbers in the chart below indicate that "The Walking Dead" #115 and "Justice League of America" #1 both sold 326,951 copies, I don't think we can say they tied for first place. We can say that while we can account for more unit sales for "Justice League of America" #1 from the monthly charts, Diamond reports that "Walking Dead" #115 outsold it. The numbers are my best guess on minimum sales based on the data available. Because of that, I'll stress that since index values were not provided for the year end list like they are for the monthly lists, these estimates are ballpark estimates and not as accurate as the monthly estimates.