On April 1, 2026, SPP extended its RTO into the Western Interconnection, which introduced new market participants, new trading opportunities, and new market dynamics. The SPP RTO expansion (RTOE) affects nearly every part of market operations in SPP—from pricing to settlements.

We are here to help you adapt, and our experts have created resources to support you from day one of this expanded RTO.

Have a question? Learn how we can help you navigate SPP RTOE.

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What Is Changing in SPP

The Southwest Power Pool (SPP) launched its RTO Expansion (RTOE)—one of the most significant structural changes in US wholesale power markets in recent years.

The initiative expanded SPP’s Regional Transmission Organization into the Western Interconnection, making SPP the first RTO to operate organized wholesale markets across both the Eastern and Western interconnections.

For market participants across the region, the expansion represents more than a geographic shift. It introduced new pricing nodes, additional trading opportunities, and changes to how data is published—while also increasing complexity across market participation, settlements, and operational workflows.

Market leadership

Market leadership

For more than 15 years, SPP participants have relied on our expertise through major market changes—supporting both market understanding and evolving operational demands. We’re focused on always providing trusted data and insights.

Quality data

As a leader in power market data and analytics, we empower customers with access to the latest SPP RTOE information—including new nodes, pricing, and system conditions—to inform short- and long-term decisions.

Expert support

Our team provides ongoing guidance, resources, and hands-on support so you can adapt quickly and confidently—whether you're analyzing market conditions or managing operational processes.

Support across the bid-to-bill lifecycle

Support across the bid-to-bill lifecycle

From market activity through settlements and invoicing, we help utilities and market participants navigate the increasing complexity of RTO participation and reduce manual, cross-system effort.

Emily Merchant | Blog

SPP’s RTO Expansion Is Now Live!

Yes Energy customers can start diving into the data now! There are over 1,000 new price nodes in SPP West with both day-ahead (DA) and real-time (RT) location marginal prices (LMPs) now available.

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Data Availability

I am a Yes Energy customer. Where can I find out more about the current or future state of SPP RTOE data in Yes Energy products?

You can find out more information by going to the Yes Energy help system (Yes Energy login required). You can also reach out to your dedicated account manager or support@yesenergy.com.

Given the separate BAs, should we expect the MEC in SPP West and East to be different most of the time?

The East BAA, reported by the ISO as “SPP,” maps to an existing Yes Energy objectID= 10017060648 (name= ‘SPPISO-East’). The West BAA, reported by the ISO as “SWPW,” maps to an existing Yes Energy objectID= 10019234935 (name= ‘SPPISO-Westt’).

The MECs will relate to each other based on the status of the West DC Ties connecting the two BAAs. When the DC Ties have available capacity (unconstrained), SPP’s single market optimization will simultaneously determine flows and dispatch across both networks. The same marginal resource influences the marginal cost to serve the load in both BAAs.

If the DC ties have no available capacity (constrained), SPP's single market optimization will economically stop scheduling power to flow across the interconnections, the MEC will decouple, and the market optimization will find the generator from each specific BAA to serve the next increment of load.

Though SPP will calculate separate Marginal Energy Components (MEC) for the East and West BAAs, the two will often be economically linked. The 310 MW limited capacity of the two DC Ties is expected to be a frequent constraint.

Will there be any more RTO-wide forecasts or just separate East and West forecasts?

For many reports (wind/load forecasts, fuel mix, etc.) SPP is no longer posting the system-wide object and is just posting the data at the BAA level (called SPPISO-East and SPPISO-West in our products). Yes Energy plans to preserve the SPPISO object for continuity purposes by summing “SPPISO-East” (objectID= 10017060648) and “SPPISO-West” (objectID= 10019234935) post cutover. An SPPISO object (i.e. an ISO-wide object) is preserved for all “actuals” data. The system-wide object specific to forecast data is being worked on by our development team and will be available by the end of the day (March 31). Note, this means that before April 1, 2026, the SPPISO object will show data for SPP East, and after April 1, 2026, the SPPISO object will show data for East + West. Visit the Help System for additional details.

Do Yes Energy customers need an additional subscription to access SPP RTOE data?

The SPP RTOE data is available under the existing SPP Trading Region subscription in Yes Energy.

Will the SPP RTOE data fall under SPP access from a Yes Energy subscription standpoint?

Yes.

General Questions

How does the MTE testing environment function?

SPP coordinates structured and unstructured testing within its Member Test Environment (MTE) before large market design changes that involve executing specific base-case scenarios to simulate actions that will occur in the new settlements process.

The purpose of the MTE for the RTO Expansion is to run SWPW simulations to enable SPP, Transmission Customers (TCs), and Transmission Owners (TOs) to practice, validate, and refine the processes and systems intended for the RTOE before its production launch. We use this test data to make sure we are collecting and ingesting the format of the new reports accurately.

How do you expect the change to impact power prices in SPP as well as the amount of wind curtailment?

The new West Hub will have many fewer wind resources in its supply stack than SPP East. Therefore, SPP West is expected to have a real-time price premium over the North and South Hubs, leading to fewer prolonged low-price periods than the East. RTOE will create economic opportunity for SPP East wind resources by spreading wind generation across a larger area, allowing SPP to reduce local curtailment (albeit limited by DC tie capacity). A new Western Trading Hub facilitates better hedging against wind-driven negative prices in the expanded footprint.

Where can people access information about SPP RTOE on SPP's website?

The primary page for SPP RTOE on the SPP website is https://www.spp.org/western-services/rto-expansion/.

SPP has issued several Resource Advisories for SPP West since the RTOE go-live. Can you summarize the specific events and any common themes?

All three Resource Advisories referred to high variability caused by "wind drop events". One of the three advisories also forecasted extreme temperature swings. Managing this type of load uncertainty requires flexible capacity. SPP uses its Uncertainty Reserve product to procure upward flexible capacity to manage net load variation, particularly during the morning and evening ramp periods.

How will the Regulation Ancillary Services differ between SPP East and SPP West?

Regulation ancillary services follow the same market rules across the entire RTO footprint. However, the specific requirements, pricing, and certain settlement calculations are managed at the BAA and/or reserve zone level. For more details, see SPP Integrated Marketplace Protocols v118.1 sections 4.1.3, 4.1.5.

What changes to general congestion patterns do you anticipate once Markets+ goes live?

When Markets+ goes live, it will operate adjacent to SPP RTO West on different software and tariffs, creating a new market seam structure. There is currently Market-to-Market (M2M) coordination agreements being discussed to prevent/track uncoordinated dispatches and new loop flows, potentially increasing congestion on shared paths. The Interface LMP should reflect the cost of MCC as power is wheeled into our out of the market seem.

Congestion Revenue Rights (CRR) Changes

If the DC Tie constraints bind at the BAA-level, how will the TCR market hedge against DA congestion for the source-to-sink paths across the DC ties? There will be a transitional 4-year period after which the paths that span across the DC ties will be tradeable in the TCR Market. Unlike positions across the AC portions of the grid, positions across the DC ties will be settled as options instead of obligations, providing only financial upside to the rights holder. Rather than hedging on the marginal congestion component of the LMP to settle the paths across the seam, the DC tie segments will be settled using the DC tie shadow price. This is a significant departure from traditional congestion hedging. The DC tie shadow price represents the capability of the DC tie to relieve total system production cost. If there is no congestion on the tie, the shadow price will simply be $0/MWh.

Real-Time Interchange often leads to uneconomic trades for both SPP East and West. What improvements are being considered in the future, from a market design perspective? SPP is currently working on implementing Real-Time Dispatchable Transactions (RTDT), which will introduce dynamic scheduling using 5-minute real-time dispatch. Market participants will be able to combine RT LMPs and net actual interchange to submit price-sensitive interchange offers that clear every 5 minutes across the boundaries. This change will create a significant improvement over static hourly schedules, increasing seam transaction efficiency and yielding significant production cost savings.

As the West continues to split into new DA markets (SPP RTO West, Markets+ and EDAM), managing market seams efficiently will require formal seams agreements, or Market-to-Market (M2M) coordination. The first phase of EDAM, along with SPP's RTOE, is critical because future M2M agreements will require accurate pricing data from the interface nodes to manage data sharing, coordinate congestion management, and track transmission rights usage across the interconnected regions.

How is the TCR market impacted by SPP RTOE?

The TCR market rules will remain consistent for paths that are contained in each BAA. The nomination cap will be set by SPP West capabilities, sharing the standard business-as-usual procedure for TCRs as SPP East operations. However, the source-to-sink paths that cross the DC Ties will undergo a four-year transition period. During this time, congestion hedging will be based on long-term Transmission Service Rights (TSRs) and settled as an option. The holders of these rights will be automatically awarded. So we will not have offer/bid data for these specific paths that will not reach the TCR market until after the four-year transition period.

When was the first TCR auction that will reflect the new RTOE locations?

The SPP West footprint and three internal DC Ties first showed up in the annual ARR allocation process, which opened on April 1, 2026. RTO Expansion-related FTR data first showed up in the Annual TCR/FTR auction (results published May 22, 2026).

LMPs

Does the west expansion affect SPP South and SPP North LMPs materially? Is SPP ISO bifurcated, or is the interconnectivity meaningful enough to impact traditional SPP hub prices?

The SPP South and North LMPs have not been significantly impacted by the RTOE. We have seen an increase in congestion volatility in SPP North since the go-live, but that is likely not due to the addition of the SPP West BAA. However, we expect the dual-BAA capability of sharing wind generation and ramp flexibility across the two BAAs will help support more robust pricing signals across the ISO over time.

Is SPP using one bus or a collection of weighted buses for the two references buses used to calculate LMP? SPP distinguishes between the Reference Bus and a Trading Hub. For the reference bus, SPP uses a single imaginary "0 shift factor" point for each respective region. That will calculate the true cost of the marginal energy component (MEC) for each BAA, without any congestion or line loss.
Then the Hub (like the new SWPW Hub) is an aggregate collection of weighted physical buses. The Hub's LMP is calculated by taking the baseline MEC established by the reference bus (above) and adding the weighted average of the localized Marginal Congestion Components (MCC) and Marginal Loss Components (MLC) from all the individual nodes that make up the hub.

Market Design

Will the market rules for SPP West resources differ from those in the rest of the SPP footprint?

No. However, you should be aware of the SPP's mechanism for managing market power, which involves "Frequently Constrained Areas" (FCA). When an FCA is binding, energy offer curves are capped at 17.5% above the mitigated energy offer curve prices.

Due to the limited transfer capability across the DC ties, we can expect all resources in SPP West to qualify as pivotal suppliers, unlike SPP East where this binds for a small minority. SPP West resources will face a binding FCA, capping energy offers at 17.5% above mitigated prices. The high shift factors in SPP West indicate that even smaller resources will significantly impact specific flowgate constraints due to their substantial locational load weighting.

How is SPP going to manage the tie interconnections between west and east;, will anything change on that front? Substantial congestion between regional interfaces? Will there be LTRC and TCRs across those lines?

SPP will continue to utilize its market optimization, but will now be used to manage the asynchronous flow across the West DC Ties to dispatch the most economical resources for East and West BAAs using a single market optimization process. Each West DC Tie will be modeled in the market software as a linked withdrawal/injection pair joining the two BAAs.

The Security Constrained Unit Commitment (SCUC) will optimize the direction of the flow across the ties. Subsequently, the Security Constrained Economic Dispatch (SCED) will determine the optimal volume of the flow.

How will import/exports be settled? Will all POD adjacent to PSCO be settled at PSCO LMP?

PSCO's service territory will be almost entirely contained within the expanded SPP footprint, making its monitoring important.

PSCO Interface location is an aggregate settlement point representing the weighted average of multiple interconnection points. Therefore, not all adjacent points of delivery will settle at this interface price. Virtual bidding/offering on the interface settles at this aggregate price.

A key dynamic to watch is the impact of transmission congestion on individual paths that make up the aggregate interface pnode. If the lines into PSCO become constrained, the PNodes on the SPP side of the border will likely experience a lower (or negative) Marginal Congestion Component (MCC). Simultaneously, the "internal" PSCO price will remain high, though this internal price cannot be traded directly in SPP.

How will the interfaces work? Will it be similar to the East?

With SPP Markets+ now overlapping with CAISO EDAM, will participants who previously participated solely in SPP have the option to register under CAISO EDAM as well? Can they choose one or the other or possibly register for both?

Market participants will have to decide between participating in CAISO EDAM/EIM, SPP Markets+, or SPP ISO. Customers cannot participate in both CAISO EDAM and SPP or CAISO EDAM and SPP Markets+.

Physical Trading

Is e-tagging no longer allowed across the tie?

Correct, physical e-tagging will no longer occur across the ties and will be scheduled from market optimization.

How will interchange between SPP West and CAISO's neighboring EDAM BAAs function?

No specific changes have been made to the interchange process between SPP West and EDAM BAs. CAISO has indicated that seams management and coordination is a top priority, but there have not been any changes made to the "market-to-market" coordination process between the regions. In the near term we do not expect EDAM BAs to behave differently than other WECC BAs as a result of SPP's expansion.

Could you explain the impact of converting DC ties from scheduled interchange to internally dispatched market resources on existing transmission rights and congestion hedges? Specifically, will existing transmission service or existing FTR/TCR/ARR positions and rights tied to these paths be modified or settled differently under RTOE?

Existing legacy transmission rights are preserved and converted to SPP service.

- Miles City: reservations on the tie were already converted in 2015

- Stegall: OATT The Basin

- Sidney: OATT WAPA-RMR

- Miles City (Owned by WAPA-UGP/Basin rights): All legacy reservations were already converted to SPP transmission service when WAPA-UGP joined the Integrated Marketplace in 2015

- Stegall (Owned by Tri-State, 100% Basin capacity): Basin Electric's legacy reservations will convert to SPP OATT network service, unless the respective merchants decide to retain these rights

- Sidney (Owned by WAPA-RMR): All confirmed long-term legacy reservations will be converted to SPP transmission service

For congestion hedging, cross-tie paths will undergo a four-year transition where holders of existing long-term Transmission Service Rights (TSRs) receive automatic congestion payouts in the Day-Ahead market, settled as an option. After four years, these paths enter the standard TCR market and settle in three distinct segments: an AC source obligation, a DC tie option based on the tie's shadow price, and an AC sink obligation.

For the DC lines, how does SPP account for the efficiency of converting AC to DC to AC for the ties? Do they use a particular hurdle rate?

Hurdle rates and wheeling charges are no longer relevant on the DC ties, because the market clearing engine directly optimizes the DC lines. To account for AC-DC-AC conversion efficiency, SPP models each tie as a linked withdrawal and injection pair. The modeled injection in the receiving BAA equals the withdrawal in the sending BAA minus the physical losses across the DC tie. When the ties hit capacity, the Marginal Energy Components (MECs) decouple and congestion is settled using the tie's shadow price.

TCR/FTR Market Impacts

Has a TCR auction for the RTO Expansion area already happened? Is there real data for this already?

No, the Transmission Congestion Rights (TCR) auction has not yet happened for the SPP RTO Expansion area in the West.

The first TCR auction reflecting the RTO Expansion data will be the Annual TCR auction, with results published on May 22, 2026. Internal SPP East’s source-to-sink paths will operate like SPP TCR market but with a distinct nomination cap reflecting system capabilities. Cross-DC Tie allocation will transition over the first four years, automatically awarding rights to existing holders for stability. After this period, TCR participants can nominate and allocate cross-interconnection paths like any other source-to-sink path, meaning economic bids for these paths won't be reflected in TCR market data for four years.

How is the TCR market changing with this new tie?

However, the source-to-sink paths that cross the DC ties will undergo a four-year transition period. During this time, congestion hedging will be based on long-term Transmission Service Rights (TSRs) and settled as an option. The holders of these rights will be automatically awarded. So we will not have offer/bid data for these specific paths that will not reach the TCR market until after the four-year transition period.

Are the pricing points in the west available to market participants in the east to use for the ARR/TCR purpose?

Yes, LMP data for nodes in the West will be available to market participants in the East for ARR/TCR purposes.

When is the first TCR auction that will reflect the new RTOE locations?

The SPP West footprint and three internal DC ties will first show up in the annual ARR allocation process, which opens on April 1, 2026. RTO Expansion-related FTR data will first show up in the Annual TCR/FTR auction (results published May 22, 2026).

Virtuals/Trading

How does this affect DA and RT bilateral trading and e-tags for physical trades between counterparties?

Physical trading based on e-tags is no longer permitted for sinks or sources located within the SPP West Balancing Authority Area.

Bilateral trades that were previously path-based are now converted into financial arrangements that settle against the DA or RT LMP.

SPP West market participants can submit DA bids and offers, with settlement based on the LMP difference. Any deviations in real time will settle at the RT LMP.

Is DA bidding available? If not, when? Is the DA segregated from the current market? Is this a separate portal?

Yes, there are approximately 298 new tradable nodes in SPP West. They will be virtually traded exactly how SPP East is traded today.

How many new tradeable, settlement nodes are there for SPP RTOE?

There are approximately 300 new tradable nodes in SPP West.

What is the impact of SPP RTOE on the virtual market? When can traders place virtual trades on the SPP West nodes?

There are about 298 new tradable virtual nodes for SPP West. These nodes will be tradable in the virtual market March 31 for the first operating day April 1. The new tradable nodes for SPP West can be found here: https://portal-mte.itespp.org/pages/da-lmp-by-settlement-location (filter BAA=SWPW).

Where can we find the list of new virtual tradable nodes in the west?

The new tradable virtual nodes for SPP West can be found here: https://portal-mte.itespp.org/pages/da-lmp-by-settlement-location

Will there be new tradeable virtual nodes associated with the seven WEIS members joining SPP RTOE?

Yes, there are approximately 298 new tradable nodes in SPP West. They will be virtually traded exactly how SPP East is traded today.

What to Know and How to Prepare

What Is Changing in SPP

Why Yes Energy for SPP RTOE

Helpful Resources for SPP RTOE

SPP’s RTO Expansion Is Now Live!

SPP RTO Expansion is Live, Now What?

FAQs about Early Market Impacts of SPP RTOE

SPP RTOE: Market Impacts & Yes Energy Updates

Preparing for SPP’s RTO Expansion: What Market Participants Need to Know

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Understand where opportunity is emerging in an expanded market.

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Frequently Asked Questions on SPP RTOE