Market Regulation Services Inc. published a series of notices Friday concerning rule amendments that aim to accommodate new trading systems.

RS reports it approved a series of amendments to the trading rules back on May 24. Among the amendments are changes to accommodate the introduction of multiple and competitive marketplaces.

Among other things, these amendments require that orders which are subject to the order exposure requirements are entered on a marketplace that displays information regarding orders; clarifies various definitions and concepts to ensure that they are applicable to all markets; and, make provision for a type of order which will trade at the last sale price of a trade undertaken on a particular marketplace.

It also approved amendments to require that, subject to certain exceptions, a market participant give priority to a client order over all principal orders and non-client orders that are entered on a marketplace after the receipt of the client order: for the same security; at the same or better price; on the same side of the market; and, on the same conditions and settlement terms.

It also approved an amendment to replace the definition of a “consolidated market display” with the term “applicable market display”. The definition of “applicable market display” eliminates the requirement that the consolidated feed produced by an information processor or the information on orders and trades produced by an information vendor must contain information from the “principal market” for a particular security; and, provides that, if there is not an information processor, information provided by an information vendor may be relied upon as an “applicable market display” only if the information vendor meets the standards established by a market regulator.