Securities regulators are pushing back the implementation of new rules regarding shorts sales, failed trades, and dark liquidity to mid October.

The Investment Industry Regulatory Organization of Canada announced Tuesday it will adopt two sets of rule changes at the same time to make it easier to make the necessary systems changes.

New rules regarding short sales and failed trades were to be implemented on Sept. 1; and new rules regarding dark liquidity were due to be adopted on Oct. 10. Now, both will take effect on Oct. 15.

Under the planned implementation dates, there would have been overlapping releases of programming changes by marketplaces, and overlapping testing windows, IIROC says in a notice. And, it notes that certain marketplaces were intending to make other programming changes during this time period.

So, to facilitate the programming changes, and to allow each marketplace to have one testing window for changes, it is pushing back both implementation dates. Therefore, on Oct. 15, regulators will: repeal the tick test, and impose pre-borrow requirements for short sales made in certain circumstances. And, they will adopt the trading rule amendments to deal with dark liquidity issues, which will: among other things, require that an order trade with visible orders on a marketplace at the same price before trading with dark orders; require that smaller orders receive price improvement when trading with dark orders, and, allow IIROC to designate a minimum size for dark orders.