1. http://nodal.ercot.com 1 Nodal Stabilization Market Call December 03, 2010 4:30 PM

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 Day Ahead Settlement Statements and Invoices for Operating Day 12-1 were posted to the MIS Notification delivery issues this afternoon –11:11: Database corruption caused notification backlog and slowdown on delivery –13:30: Notifications held to correct issue and then released to clear backlog (which took time) –No notifications or data were lost –Impacts: Delay in SASM awards Delay in publishing DAM Awards (subsequent delay in DRUC) – published 14:54 http://nodal.ercot.com 4

5. What Quantity Was Traded Through the DAM A Simplistic Approach: Add up the quantities which create flows – TPO, EOO, CRR source, PTP source. Graphs shows that this gives 54,000 MW for 1 December. But this graph double counts. Consider… –PTP of 10 MW from node A to node B –PTP of 10 MW from node B to node A. These PTPs contribute a net flow of zero between A and B, but the graph adds them to give 20 MW. http://nodal.ercot.com 5

6. What Quantity Was Traded Through the DAM http://nodal.ercot.com 6 C PTP sink: 10 MW PTP sink: 5 MW Net flow out: -10 MW Net flow out = -15 MW B EOO: 15 MW EOB: 45 MW PTP source: 15 MW PTP source: 5 MW A TPO: 30 MW PTP source: 10 MW PTP sink: 15 MW Net flow out: +25 MW NodeSum of sources Sum of sinks Net flowAbs(net flow)0.5 Abs(net flow) A10+30=401540-15=252512.5 B15+15+5=354535-45=-10105 C010+5=150-15=-1552.5 Hedged Energy Flow25 25 MW flows into network, 25 MW flows out. This measurement has no double counting.

7. What Quantity Was Traded Through the DAM The Hedged Energy Flows is formed by summing over all settlement points half the absolute value of the net flow into the network. No PTP or CRR data is used in forming the graph on the right except via impact on net flows. The Demand Forecast is a measure of the load to be supplied by the network and hence is a good basis of comparison. It is true that there is no guarantee that a PTP award will be matched by supply/demand in real-time, but this is the best measure we have that avoids double counting. http://nodal.ercot.com 7 This is the net additional usage of transmission capacity by CRR/PTPs.* *CRR Options carried to RT and PTP Obligation bids awarded in the DAM

8. http://nodal.ercot.com 8 Calculation of Hedged Energy Flows For each settlement point (SP): Absolute Value(Total DAM energy bought + Total PTP Obligation Bid awarded sinking at the SP + Total CRR Offers not awarded in DAM sinking at the SP - Total DAM energy sold [note: includes TPOs and EOOs awarded]- Total PTP Obligation Bid awarded sourced at the SP - Total CRR Offers not awarded in DAM sourced at the SP)/2. Then add that amount up for all settlement points for each hour to get the net energy transactions system-wide.

9. http://nodal.ercot.com 9 FAQ Q: Does DAM check the COP resource status? A: DAM uses the COP in two ways. 1) The HSL/LSL contained in the next day’s COP is used to determine max/min TPO award quantities. 2) The resource status for the rest of the current day’s COP is used to determine the initial condition (online/offline status) for the start of the next day. DAM does not look at your COP resource status for the next operating day. If your unit is planned to be OUT for the next day, do not submit a TPO into the DAM for any hours for which the unit planned to be OUT

10. http://nodal.ercot.com 10 FAQ Q: Why was my fixed quantity block offer awarded below my offer price? A: Fixed bids/offers cannot set the price, which means that the offer could clear below the offer price (or bid above the bid price), or not clear even though the LMP supports it, when the offer/bid is marginal. This is a known outcome of fixed bids/offers. For more info on this, see Appendix 7 of the DAM requirements, posted at http://nodal.ercot.com/docs/pd/mms/pd/damsasmr/mms_dam_and_sasm_req_09q1_v4_0 %20%28blackline%29.doc. http://nodal.ercot.com/docs/pd/mms/pd/damsasmr/mms_dam_and_sasm_req_09q1_v4_0 %20%28blackline%29.doc Recommend utilizing ‘variable’ quantity instead if it is desired to avoid this outcome.

11. http://nodal.ercot.com 11 Questions?