Introduction

Cboe members may use the TOP protocol to receive real-time top of book quotations direct from Cboe. Market data received through TOP is more timely than obtaining the same data via the consolidated feed. The TOP protocol offers approximately 66% reduction in the number of events and 84% reduction in the number of bytes of application data sent, compared to the Cboe TCP PITCH protocol.

The quotations received via TOP provide an aggregated size and do not indicate the size or number of individual orders at the best bid or ask. Hidden orders are not represented in TOP. The TOP protocol also provides last trade price and size and cumulative volume data.

This specification will be the standard TOP specification used for Cboe BYX Exchange, BZX Exchange, EDGA Exchange, and EDGX Exchange platforms within the NY5 data center.

Complete depth of book market data can be received via the Cboe PITCH protocol.

TOP cannot be used to enter orders. For order entry, refer to the appropriate Cboe FIX or BOE Specification.