eBay Active Buyers

All users who bid on, bought, listed or sold an item within the previous 12-month period. Users may register more than once, and as a result, may have more than one account.

eBay defines this as:

All buyers who successfully closed a transaction on our Marketplace platform within the previous 12-month period. Buyers may register more than once, and as a result, may have more than one account.

Last reported quarter 2021 Q4 it was 147 million, down by -9% year-over-year from 162 million.

Source: eBay Quarterly Results.