The Securities and Exchange Commission Regulation NMS Rule 610 requires, among other things, fair and non-discriminatory access to quotations and requires trading centers to establish, maintain and enforce written policies and procedures reasonably designed to prohibit members from locking or crossing markets. Rule 611 prohibits trade-throughs, which are trades in a security in one market at prices inferior to those for the same security in another market. The trading phase date for Rule 611 trade-through protection will now commence on March 7. The pilot stock phase date for compliance with Rules 610 and 611 for 250 NMS stocks will now commence on July 9. The all stocks phase date for full industry compliance will now commence on August 28 and must be completed by October 8.