Electricity trading across South-East Europe shifted during the final weeks of December 2025 and the opening month of January 2026, with organized power markets playing a larger role in price discovery, arbitrage and risk management. The period followed several years in which bilateral contracting, administrative interventions and risk aversion shaped regional behavior. Market activity in the winter window was associated with higher liquidity, more active cross-border flows and price signals increasingly linked to regional fundamentals.
Prices moved sharply within weeks while volumes did not collapse, according to activity on exchanges spanning Hungary, Romania, Serbia and Bulgaria. The regional pattern described was of interconnected trading hubs where spreads, congestion and flow patterns could be monetized in real time. Four venues—HUPX, OPCOM, SEEPEX and BELEN—were highlighted as defining the regional trading map during the winter of 2025–2026.
Liquidity return on organized markets in late 2025 and early 2026
The defining feature of December 2025 and January 2026 was a return of liquidity to organized markets. The change was described as different from earlier winters in which high prices coincided with thinning order books as participants moved toward bilateral cover. In winter 2025–2026, elevated prices were reported to coexist with rising traded volumes.
In Serbia, activity on SEEPEX showed January volumes consistently between 12.9 and 16.5 GWh per day. That range implied total monthly traded volumes of approximately 420–450 GWh. The same period was described as a material year-on-year increase, alongside greater willingness by Serbian generators, traders and large consumers to use day-ahead price formation rather than relying exclusively on fixed bilateral contracts.
Day-ahead clearing prices on SEEPEX during January 2026 ranged from lows near €67/MWh on mild, hydro-supported days to highs above €125/MWh during colder periods with tighter system margins. High prices did not reduce participation, with volumes remaining robust even on peak-price days. The reported pattern indicated continued engagement with market mechanisms and risk management.
HUPX sets price expectations for regional spread trading
HUPX in Hungary continued to function as a central reference point for South-East Europe power trading. Average daily day-ahead volumes were typically in the 70–80 GWh range, making it described as substantially more liquid than most neighboring exchanges. The depth was cited as supporting regional price expectations and providing a basis for forward hedging and bilateral indexation.
In December 2025, average Hungarian day-ahead prices hovered around €110–120/MWh. The level reflected a winter premium attributed to higher demand, carbon costs and marginal thermal dispatch. While elevated versus historical averages, the prices were reported as lower than crisis-era extremes and associated with smoother intraday profiles.
The role of HUPX extended beyond absolute levels into spread evaluation across smaller exchanges. When Serbian or Bulgarian prices diverged from Hungary, the decision framework shifted toward whether cross-border capacity and congestion pricing supported the trade. This was contrasted with earlier periods when physical constraints and regulatory frictions often reduced the practical relevance of such comparisons.
OPCOM shows bidirectional flows with Hungary and Bulgaria
OPCOM in Romania combined domestic market activity with transit dynamics between Central and South-East Europe. During December 2025, average day-ahead prices clustered around €115–120/MWh, broadly aligned with Hungary while showing episodic divergences tied to domestic generation and cross-border constraints. The emphasis in the winter window was placed on flow directionality rather than only price levels.
Romania exported and imported electricity with Hungary in alternating patterns that could occur within the same week. The bidirectional behavior was presented as an indicator of market integration, suggesting that price differences were narrow enough—and transmission available enough—for traders to respond dynamically to short-term fundamentals. The same period described Romania as enabling offsetting positions taken on OPCOM against HUPX or BELEN.
BELEN participation increases alongside regional price tracking
BELEN, Bulgaria’s exchange venue, was described as historically less liquid than northern neighbors. Winter 2025–2026 did not change that ranking immediately but showed a trend toward deeper participation. Prices on BELEN tracked regional movements closely, with winter averages broadly aligned with Romania and Serbia while exhibiting higher volatility during periods of domestic constraint.
The growing relevance of BELEN was linked less to absolute volume than to its role connecting Balkan markets with Greece and its interaction with Romanian flows. As interconnector utilization improved, BELEN prices increasingly reflected regional supply-demand balances rather than isolated Bulgarian conditions. This was described as improving usefulness for cross-border strategies when congestion premiums emerge.
Cross-border corridors drive price formation across the region
A central theme during winter 2025–2026 was the role of cross-border flows in shaping price formation across South-East Europe. The region was described as no longer operating as semi-isolated national markets. Instead, price signals were reported to propagate along corridors connecting Hungary, Romania, Serbia and Bulgaria.
During December 2025, utilization of interconnectors between Hungary and Romania was consistently high, with flows reversing direction depending on relative price spreads. Serbia’s position was described as particularly sensitive: when SEEPEX prices traded below HUPX, exports toward Hungary became attractive; when Hungarian prices softened or Serbian prices spiked, imports flowed in the opposite direction.
The reported effect of this flow-driven behavior included faster price convergence across the region by reducing extreme local deviations. It also shifted trading strategy toward relative price positioning and congestion management rather than absolute forecasting alone. Traders able to identify when capacity binds could monetize short-lived spreads that might have persisted longer under less integrated conditions.
January volatility tied to demand drivers, hydro conditions and thermal costs
Volatility during January 2026 was described as structured rather than chaotic. Price swings were tied to identifiable drivers including cold spells increasing demand, variations in hydro availability, and the marginal role of thermal generation influenced by fuel and carbon costs. This contrasted with earlier crisis periods where prices were attributed to panic, regulatory shocks or extreme scarcity.
The described market response meant intraday and day-ahead markets rewarded active management aligned with those drivers. Industrial consumers with flexible load could adjust consumption during high-price hours. Generators optimized dispatch against short-term price signals while traders used intraday approaches to capture differences between forecasted conditions and realized outcomes.
The presence of volatility without systemic stress was presented as consistent with market functioning where participants trust clearing mechanisms and liquidity is sufficient to absorb shocks without withdrawal. The same winter window was used to characterize organized exchanges across SEE as indispensable for price discovery and risk management.
Trading strategies adapt as liquidity supports hedging and spread positions
The winter of 2025–2026 confirmed several operational realities for professional participants: organized exchanges supporting price discovery and risk management; cross-border awareness acting as a key determinant for trading profitability; and sufficient liquidity in core hubs enabling more sophisticated strategies. Those strategies included spread trading, shape optimization and portfolio hedging.
Industrial consumers were also described as adapting procurement behavior by using exchange prices as reference points for decisions on procurement timing and contract renegotiation instead of treating exchange pricing solely as a threat. This behavioral shift was described as reinforcing liquidity by keeping exchanges central to market activity rather than peripheral platforms.
Toward further integration with the EU internal electricity market
The dynamics observed in December 2025 and January 2026 were linked to a trajectory toward closer integration between South-East Europe’s market structure and the EU internal electricity market framework. As integration progresses, distinctions between “regional” and “core” European trading hubs were expected to blur further based on ongoing initiatives mentioned in the source facts: market coupling efforts, improved capacity calculation approaches and regulatory alignment.
The same period’s description indicated that opportunity would increasingly depend on speed, information access and operational execution rather than only geographic arbitrage opportunities. Congestion was described as persisting but becoming more transient and tradable under conditions shaped by cross-border flows.