1. http://nodal.ercot.com 1 Market Trials Open Market Participant Call Weekly Kick Off Aug 09, 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 representative of a post go-Live scenario –Next Full System Market and Reliability Test will occur the week of 8/16/2010 Details to be discussed at NATF today and confirmed via a Market Notice 1 week in advance of the test Please send any updates to contact information to markettrials@ercot.com (also let ERCOT know if a primary contact will be on vacation or out for any reason the day of the test) markettrials@ercot.com DAM / RUC –Week 15 (of phase 5): DAM will run seven times this week for operational days 8/10/2010 through 8/17/2010 –SASM will be run when necessary –HRUC will occur 24x7 CRR –08/09/2010 – ERCOT posts 2011-2012 Annual Auction results –08/10/2010 – ERCOT releases annual auction locked funds –08/10/2010 – ERCOT posts annual auction invoice –08/13/2010 – September Model w/ outages posted to MIS Outage Scheduler –Realistic outages for effective operational dates Tuesday - Saturday –Test Outages continue for effective dates Sunday, Monday –REMINDER: on 8/13 ERCOT will purge all test outages and run the Zonal to Nodal import process –QSEs and TSPs will be expected to begin dual entry (on Monday 8/16) for Outages effective for September and post Go-Live (12/1/2010). Week 15 Note: Dates are DAM execution daysEveryday Objective Exercise 7 days / week Network Constraints Included DAM 7x week DAM submissions No guardrails COP Updates Reflect Nodal DRUC W/ each DAM HRUC 24X7 WRUC Per protocols SASM As needed Op Scenarios

4. Follow-up and Reminders If a TSP does NOT want ERCOT to pump their outages on 8-13-10 –Send an email to MarketTrials@ERCOT.com by COB today stating they do NOT want to pump their outages. MarketTrials@ERCOT.com –Include your DUNS number in the email. If ERCOT does not receive an email, we will run the pump for those TSPs. All of the ERCOT test Verifiable Costs have been removed. Only officially approved Verifiable Costs are in NPROD. –DAM offers could be rejected if startup and min energy costs are above generic verifiable costs (starting today). COPs should reflect Nodal data –To allow MPs to exercise their systems while running DAM for 7 days this week. http://nodal.ercot.com 4

5. Follow-up from Friday’s RTM Call During the 24 hour test, ERCOT relieved units for two QSEs of their AS obligations –The units were needed by SCED to resolve congestion. –Total of 125 MWs of Regulation Up and 70 MWs of Responsive Reserve. –ERCOT operators followed the appropriate course of action. Follow-up information on base point deviations –Communication of GREDP analysis from the 24 hour tests starting today. –ERCOT is planning to discuss additional 24 hour test results on the 8/12 RTM call. Follow-up on SCED dispatch of QSEs on Output Schedules http://nodal.ercot.com 5