Market wide Triact handles around 6 or 7% of trading in Canada....but with RVX its over 50% today, and yesterday as well I believe.  

Here are just some advantages to pushing trading volume over this platform:

Tactical Advantages

• No Public Book Display: MATCHNow is a fully confidential dark book, displaying no information to the public on participants, order size or pricing. Participants cannot see or modify any orders other than their own. Large orders can be submitted without fear of disclosure.

• Zero Market Impact: Information leakage can be virtually eliminated through anonymous trade reporting. Trades for unattributed orders are publicly reported with broker # 001; otherwise, trades print under the regular (TSX) broker number. 5 Cdn Dealers (Subscribers) Cdn Clients / US Dealers (Direct Access Clients) 3 rd Party Networks (Access Vendors) MATCHNow Subscriber Agreement CdnCdn DeaDealelerrs ((Sububscrriibeberrs)) CdnCdnClieClientnts // USUSDeaDeallerrs ((DiDirrececttAccesess ClCliienentsts)) 3 rdrdPartrty NeNetwt ororks ((Accesess Venendodorrs)) Direct Access Terms Network Connectivity Agreement

• Execution Control & Risk Management: MATCHNow combines a number of unique features that enable the trader to automate key trading criteria. With these tools, traders can control execution, minimize risk and achieve overall trading goals. See below for details: Order Attributes and Parameters for Liquidity Providers.

• Broker Preferencing: Broker Preferencing is applied to both regular and anonymous trades. MATCHNow offers brokers a venue to help facilitate unintentional crosses from multiple trading groups, allowing institutional trades to automatically trade against incoming retail flow before the displayed markets.

http://matchnow.ca/assets/MATCHNow-In-Detail.pdf