You can subscribe to all tickers and all events simultaneously in one WebSocket feed. You can subscribe to all tickers using the “” character. For example, to subscribe to trades for the entire US equities universe, you can use {“action”:”subscribe”, “params”:”T.”} You can also use a comma separated list of events + tickers to subscribe to a custom list of tickers/events, such as {“action”:”subscribe”, “params”:”T.AAPL, Q.MSFT, AM.F, A.SPY”} The maximum character limit you can insert in the subscribe message is 1MB worth of characters.

Options Quote Subscription Limit

There is a limit of 1,000 contracts for Options Quotes (Q.O:*) per WebSocket connection. Wildcard subscriptions such as Q.O:SPX* are not supported for Options Quotes. If you need to subscribe to more than 1,000 options contracts, you will need to use multiple WebSocket connections.