1. http://nodal.ercot.com 1 Market Trials Open Market Participant Call Weekly Kick Off May 10, 2010

2. http://nodal.ercot.com 2 Antitrust Admonition ANTITRUST ADMONITION ERCOT strictly prohibits Market Participants and their employees who are participating in ERCOT activities from using their participation in ERCOT activities as a forum for engaging in practices or communications that violate the antitrust laws. The ERCOT Board has approved guidelines for members of ERCOT Committees, Subcommittees and Working Groups to be reviewed and followed by each Market Participant attending ERCOT meetings. If you have not received a copy of these Guidelines, copies are available at the Client Relations desk. Please remember your ongoing obligation to comply with all applicable laws, including the antitrust laws. DISCLAIMER All presentations and materials submitted by Market Participants or any other Entity to ERCOT staff for this meeting are received and posted with the acknowledgement that the information will be considered public in accordance with the ERCOT Websites Content Management Operating Procedure.

3. http://nodal.ercot.com 3 This Week’s Activities RTM / LFC –Submit Energy Offer Curves 80-120% of cost –Full System LFC 2hr Closed Loop Test Next Week Will confirm date (5/19, 5/20, 5/21) 2 days prior to test Re-confirm w/ market notice the day of test Hotline and WebEx will server as lines of communication (info included market notice DAM / RUC –Week 2 (of phase 5): DAM will run on 5/11/2010 and 5/13/2010 Note that this week will only be 2 DAM runs –Note that for this week only, ERCOT will truncate fixed quantity Energy Only Offers / Bids to remove any fractional MWs to work around a known issue This issue is expected to be resolved with a patch release this week CRR –June Monthly Auction Notice delayed A defect discovered during the running of the June True-Up allocation has delayed the posting of the June Auction notice ERCOT is working with the vendor to resolve and expects resolution by EOB Tuesday 5/11/2010 Outage Scheduler –5/10/2010 – Zonal to Nodal import will run today –Realistic outages only during the business week –Test Outages for effective dates Saturday, Sunday and June only Week 2 5/10/2010 Day Ahead / RUC / SASM Objective Ramping to DAM 5x / week Network ConstraintsIncluded Self AS requestedActual DAM2x / week Load Bid MW Requested 80% Tue/120% Thurs forecasted load Virtual Bids / Offers Up to 10 transactions/QSE/hr PTP Obligations Up to 5 bids totaling 50 MW unless the bid represents QSE's load NOIE CRR OffersAllocated CRRs only DRUC DRUC w/ each DAM HRUC HRUC Executed Limited WRUC None SASM SASM Executed COP Updates After DAM, DRUC HRUC, SASM Operational Scenarios Market TimelineProtocols - Best Effort CreditIntegrated

4. http://nodal.ercot.com 4 Reminders / Follow-ups Counter Party Certificates –Reminder that ERCOT will be sending Counter Party (CP) certificates to all QSEs that have not yet received them this week –MP USAs will receive the CP USA certificate –Once downloaded, the MP USA may then generate user certificates –A CP user certificate is required to access ACL and Credit reports for that entity's QSE, Sub-QSEs and CRRAH The role CRR_EXTRACTS is required –ERCOT will post a copy of the user guide for managing the MP USA and generating user certificates to this meeting’s web page at: http://www.ercot.com/calendar/2010/05/20100510-MT http://www.ercot.com/calendar/2010/05/20100510-MT ERCOT is asking that on 5/13/2010, Market Participants submit Energy Offer curves that deconstruct their Zonal offers –This is to rehearse what we will be performing for the 2hr LFC test next week –The spreadsheet tool (“Curve Creator”) for deconstructing your Zonal offers is posted at http://www.ercot.com/calendar/2010/05/20100506-MThttp://www.ercot.com/calendar/2010/05/20100506-MT