Exchange Market Size
From ACT Wiki
Stock exchange - brokers - firm quotes.
(EMS).
Exchange Market Size relates to the quotations provided by brokers on an exchange.
It is a maximum deal size at which the broker is obliged to transact, at the price the broker is quoting.
For equities, the EMS is determined as a rounded number of equity shares - for example 50,000 shares.
If the client wants to trade a larger number of shares, the broker may decline to transact, or change their quote.
The larger the market capitalisation of a stock, the larger the EMS.
The EMS was formerly known as the Normal Market Size (NMS).