Likely the NYSE, they've decided to make some money off of algorithmic trading by charging a non-display fee, where it costs thousands of dollars per month to u

Likely the NYSE, they've decided to make some money off of algorithmic trading by charging a non-display fee, where it costs thousands of dollars per month to use stock quotes for anything other than displaying to a human, and have been on a warpath enforcing it, causing a large fight between the NYSE and Bloomberg, Citadel, etc. with lots of lawyers and government regulators involved. I can't imagine they're happy about people possibly using Google or Yahoo Finance APIs for similar purposes either (since most of the uses of market data APIs are probably for non-display use). http://www.businessinsider.com/bloomberg-letter-targets-nyse-trading-fee-changes-2017-4 http://www.businessinsider.com/bloomberg-letter-targets-nyse... https://www.nyse.com/publicdocs/nyse/data/Policy-NonDisplay_PDP.pdf https://www.nyse.com/publicdocs/nyse/data/Policy-NonDisplay_...