Cboe
Cboe stands for the Chicago Board Options Exchange, though the company now goes by the initials alone since it operates far more than one exchange today. It is one of the largest operators of exchanges and trading venues in the United States, offering trading in options, futures, and other listed products across stocks, indexes, and other assets.
Cboe's roots are in options trading. It opened in 1973 as the first marketplace built specifically for standardized, exchange-listed stock options, replacing the informal and thinly regulated way options had traded before then. That original venue, the Cboe Options Exchange, is still one of its core businesses, but the parent company has since expanded through acquisitions and now runs multiple equities and options exchanges as well as well-known market volatility products.
The nuance that trips people up is the difference between "Cboe" the company and "Cboe Options Exchange" the specific market. A trader might see "Cboe" mentioned in the context of a stock trade (because Cboe also runs equities exchanges), in the context of options, or in the context of the VIX, the widely watched index that measures expected volatility in the S&P 500 and which Cboe calculates and lists products on. Depending on the context, "Cboe" can mean the parent company, one particular exchange it operates, or the source of a specific data feed or index.
For a beginner, the practical takeaway is that when you see "Cboe" quoted as the source of a price, an option quote, or a volatility reading, it is naming the venue or the calculation source, not a strategy or an indicator you build yourself.
This term depends on a rule or threshold that changes over time, so no specific figure is quoted here. Confirm Cboe's current corporate structure and full list of exchanges/products it operates (equities, options, futures, index products) against Cboe's own official 'about' or investor relations page, since the company has grown through acquisitions and its lineup of venues changes over time.
Day traders who trade options or watch the VIX interact with Cboe's markets and data directly, so knowing which Cboe venue or product is quoting a price helps explain why quotes, spreads, or halts might differ from what you see referencing another exchange.
A trader checking the implied volatility on SPX options sees the quote sourced from "Cboe" — this means the price and the options contract itself are trading on the Cboe Options Exchange, one of the venues the company operates, rather than being calculated independently by a broker.
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