Google Possum

Google Possum, a significant unconfirmed algorithm update deployed in 2016, aggressively targeted the filtering of local search results. Its primary impact was to prevent multiple businesses owned by the same company, or businesses sharing the exact same physical address (like a massive office building), from dominating the Local Pack simultaneously. Possum heavily diversified the local results, forcing Google to display a wider variety of businesses. It also made the physical location of the searcher (proximity) a far more sensitive and heavily weighted ranking factor for local queries.

Google Possum Simplified

Google Possum was a change Google made to stop one massive company from taking up all the spots in a local map search. It forced Google to show a wider variety of businesses, and it made the exact physical location of the person searching much more important.