Yahoo options chain pricing vs stock broker pricing

External question — Quantitative Finance Stack Exchange Author: Matt Original post: https://quant.stackexchange.com/questions/32507 License: CC BY-SA 3.0 — https://creativecommons.org/licenses/by-sa/3.0/ Adaptation: HTML converted to plain text; contact email addresses removed. I am having hard time understanding the price difference of yahoo option chains. For example: Yahoo shows for TWTR FEB 17, 2017 CALL @16.50 option Strike Last Price Bid Ask 16.50 0.10 0.09 0.10 Whereas at a stock broker (ex: tastyworks) for TWTR FEB 17, 2017 CALL @16.50 option Strike Bid Ask 16.50 0.30 0.31 Whereas at a stock broker (ex: thinkorswim) for TWTR FEB 17, 2017 CALL @16.50 option Strike Bid Ask 16.50 0.28 0.29 I can understand the difference between thinkorswim vs tastyworks but not yahoo. Where does the difference between comes from ? Is yahoo delayed ? If that's the case why people bother reading yahoo options?