1. http://nodal.ercot.com 1 Nodal Stabilization Market Call December 06, 2010 10:30 AM

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 General Updates / Reminders

4. General Reminders / Updates Based on feedback, ERCOT will continue daily Market Calls through the end of December –Daily calls will be held once / daily at 4:30 PM Monday through Thursday starting on 12/8 –Friday calls will continue to be held at 9:00 AM –No calls will be scheduled on the weekend –ERCOT will hold the last 10:30 AM market call on Tuesday 12/7 – These calls will be focused on issues and MP questions (detailed market analysis will no longer be on the agenda starting on 12/8) –ERCOT.com Calendar to be updated with meeting information http://nodal.ercot.com 4

5. General Reminders / Updates Weekend Issues 48 hour Disclosure Reports were posted late due to significantly long run times –Friday, December 3rd – Saturday, December 4th –Both days of postings were available for download on Saturday, December 4 th Some 48 hour Disclosure Reports first run dates required by Protocols will be delayed until late December Both lists are available at the end of this presentation http://nodal.ercot.com 5

6. http://nodal.ercot.com 6 Day Ahead Market

7. DAM Operating Day December 4 http://nodal.ercot.com 7

8. DAM Operating Day December 4 http://nodal.ercot.com 8 This is the net additional usage of transmission capacity by CRR/PTPs.

9. DAM Operating Day December 4 http://nodal.ercot.com 9

10. DAM Operating Day December 4 Top 5 unique binding constraints (based on shadow price) http://nodal.ercot.com 10

11. DAM Operating Day December 5 http://nodal.ercot.com 11

12. DAM Operating Day December 5 http://nodal.ercot.com 12

13. DAM Operating Day December 5 http://nodal.ercot.com 13

14. DAM Operating Day December 5 Top 5 unique binding constraints (based on shadow price) http://nodal.ercot.com 14

15. DAM Operating Day December 6 http://nodal.ercot.com 15

16. DAM Operating Day December 6 http://nodal.ercot.com 16

17. DAM Operating Day December 6 http://nodal.ercot.com 17

18. DAM Operating Day December 6 Top 5 unique binding constraints (based on shadow price) http://nodal.ercot.com 18

19. Price Correction for DAM Operating Day Dec 4 Price Validation Tool identified issue with DAM SPPs on OD Dec 4 th for 2 resource nodes: –Root cause identified –Gap in shift factors during price calculation only (post solution process) –Program fix identified, with interim flagging of issue to identify issue prior to publishing results Communications –Notification sent in MIS this morning –Corrected prices posted at http://www.ercot.com/mktinfo/prices/pricecorrections/ http://www.ercot.com/mktinfo/prices/pricecorrections/ –ERCOT will send broader market notice with detailed information http://nodal.ercot.com 19

20. Price Correction for DAM Operating Day Dec 4 http://nodal.ercot.com 20

21. Price Correction for DAM Operating Day Dec 4 http://nodal.ercot.com 21

22. Price Correction for DAM Operating Day Dec 4 http://nodal.ercot.com 22 DELIVERY_DATEDELIVERY_HOURSTL_PNT_NAMEOriginal_SPPCorrected_SPP 12/4/201018CHE_LYD32.3732.49 12/4/201019CHE_LYD38.1138.20 12/4/201020CHE_LYD35.3635.59 12/4/201021CHE_LYD31.4231.64 12/4/201022CHE_LYD31.0432.05 12/4/201018CHE_LYD232.3732.49 12/4/201019CHE_LYD238.1138.20 12/4/201020CHE_LYD235.3635.59 12/4/201021CHE_LYD231.4231.64 12/4/201022CHE_LYD231.0432.05

23. http://nodal.ercot.com 23 Real Time Market / LFC

24. Real Time Market Update http://nodal.ercot.com 24

25. Real Time Market Update http://nodal.ercot.com 25

26. http://nodal.ercot.com 26

27. Real Time Market Update http://nodal.ercot.com 27

28. Real Time Market Update http://nodal.ercot.com 28

29. Real Time Market Update http://nodal.ercot.com 29

30. http://nodal.ercot.com 30 DRUC  Execution Time = 8 minutes  1 resource commitment  No resource de-commitment  2 unique binding constraints; no constraint violation  DI_DWHI8 : RINCON_WHITE_2_1 (HE1-6, HE8-18)  SGLDSUN8 : 6215__A (HE8)

31. http://nodal.ercot.com 31  Average Execution time = 10 min (max = 19 min at 12/4 9:03:01 PM)  No resource commitment  No resource de-commitment  2 unique binding constraints; no constraint violation  DI_DWHI8 : RINCON_WHITE_2_1(HE1-24)  SGLDSUN8 : 6215__A(HE3-8) HRUC

32. Real Time Market Update http://nodal.ercot.com 32

33. Real Time Market Update http://nodal.ercot.com 33

34. http://nodal.ercot.com 34

35. Real Time Market Update http://nodal.ercot.com 35

36. Real Time Market Update http://nodal.ercot.com 36

37. Real Time Market Update http://nodal.ercot.com 37

38. http://nodal.ercot.com 38 Execution Time = 6 minutes 1 resource manual commitment No resource de-commitment 4 unique binding/violated constraints SALAN_S8 : AIRLIN_CABANI1_1binding (HE21-24) SFORGIL8 : GILLES_8AT1binding (HE8) SGLDSUN8 : 6215__Abinding (HE7-8) SNCWMOS8 : ODNTH_FMR1binding (HE 7-9, 23) violated (HE 10-16) DRUC 12/5

39. http://nodal.ercot.com 39 HRUC 12/5 Average Execution time = 12 min (max = 19 min at 12/4/2010 9:03:01 PM) 6 resource commitments No resource de-commitment 7 unique binding/violated constraints SALAN_S8 : AIRLIN_CABANI1_1 SFORGIL8 : GILLES_8AT1 SGLDSUN8 : 6215__A SNCWMOS8 : ODNTH_FMR1 SPZGN8 : GT_MID90_A XMGS58 : MGSES_MR2H XMGS58 : MGSES_MR2L

40. http://nodal.ercot.com 40 Settlements and Billing

41. Day-Ahead Market Settlement Statements & Invoice Posting Dates –DAM OD 12/01 posted on Friday 12/3 –DAM OD 12/02 posted today Monday 12/6 –DAM OD 12/03 – 12/05 will post tomorrow 12/7 Reminder: QSE’s who intend to Shadow Settle must subscribe to extracts. http://nodal.ercot.com 41

42. http://nodal.ercot.com 42 Questions?

43. 48 hour Disclosure Reports Now Available on MIS http://nodal.ercot.com 43

44. 48 hour Disclosure Reports first run dates required by Protocols will be delayed until late December 2010 http://nodal.ercot.com 44