Total sales for all eBay marketplaces.
eBay defines this as:
Total value of all successfully closed transactions between users on our Marketplace platform during the period regardless of whether the buyer and seller actually consummated the transaction. We believe that GMV provides a useful measure of the overall volume of closed transactions that flow through our platforms in a given period, notwithstanding the inclusion in GMV of closed transactions that are not ultimately consummated.
Last reported quarter 2017 Q3 it was $20.52 billion, up by 9% from $18.91 billion the same quarter a year before.
Since 2015 it increased by 1%, from $78.10 billion to $79.25 billion in 2016.
Source: eBay Quarterly Results.