From Vice News:
Each NYC yellow taxi needs a medallion to operate legally. New York City caps the total number of medallions, and there are fewer than 14,000 of them available today. For decades, that scarcity made medallions a seemingly safe investment.NYC taxi medallions are worth only as much, or as a little, as buyers are willing to pay for them. And with the rise of Uber, Lyft, and other competitors that don’t require costly permits, many medallion owners are facing a a disturbing reality: taxi medallion prices have plummeted in the past three years.