1 Nodal Stabilization Market Call December 16, 2010

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.

General Updates / Reminders Some RTM SPPs affected due to incorrect FIP/FOP –System issue caused the MMS to use the Fuel Index Price (FIP) and Fuel Oil Price (FOP) from the previous day instead of the current day –Days Impacted were 12/1/2010, 12/8/2010 and 12/13/2010 –Mitigated Offer Cap was incorrect on these dates –Base Points were not impacted –System Lambda and LMPs were not significantly impacted –ERCOT will not recommend price corrections to the Board of Directors Delayed and missing postings for Resource AS Supply Insufficiency at 1430 Report –The Resource AS Supply Insufficiency at 1430 Report has incurred posting delays and some missing postings for December 1 – 14, 2010 –The following posting days were made available on Monday, December 13, The reports were posted late due to extensive data validations being performed: 12/2, 12/4, 12/5, 12/7, 12/8, 12/9 –The following reports were not and will not be made available due the reporting running prior to Market Participants receiving their DAM awards: 12/1, 12/3, 12/6 –The following posting days were not made available and will not be made available due to system issues: 12/10, 12/11, 12/12, 12/13 Due to Board approval of NPRR293, ERCOT is required to implement a new report, Day-Ahead Market Total PTP Obligation Bid Awards by Settlement Point –This report will be manually posted by ERCOT staff on both the MIS and ERCOT.com as soon as possible after each DAM, until the report is automated to become part of the DAM publishing timeline with other reports. It is anticipated that the report will be posted by end-of-business each day (including weekends/holidays) but may be delayed if there are resource constraints on some days. On the MIS under Day-Ahead Market Results On ERCOT.com under Day-Ahead Market Results Reports at –Today we will post two reports, one for yesterday’s DAM and one for today’s 3

General Updates / Reminders Real Time price correction for 12/15 –Affected time period: SCED Intervals 00:10, 00:15, and 00:20 Settlement Point Price intervals 00:15 and 00:30 –Root Cause: Real-Time Contingency Analysis (RTCA) software ran at 00:07, but the new State Estimator Electrical Bus mapping table from the 12/14 23:56 database load did not transfer to the RTCA software until after 00:20 This resulted in inaccurate RT Electrical Bus LMP and SPPs due to the absence of electrical bus shift factors for this time period This did not affect the Base Points and the LMPs sent through ICCP since these are based only on Resource Node Shift Factors –Resolution: Price correction has been posted for the 00:15 and 00:30 SPP intervals The database load procedure will be modified such that the RTCA software will not be run until all the appropriate data tables have finished being transferred Data transfer delays and software enhancements are also being investigated 4

CMM Credit Transition 5

6 Questions?