Does Sharing a Stadium Cancel Home Advantage? What Groundsharing Clubs Reveal

Groundsharing is the arrangement in which two professional clubs use the same stadium as their home ground, as Inter and AC Milan do at San Siro. A common belief holds that when two such clubs meet, home advantage disappears. Results from these fixtures, logged on RubiScore (https://rubiscore.com) like any other match, suggest the reality is more nuanced. This article examines the myth, why people believe it and what the evidence actually supports.

The Myth

The claim is simple. Home advantage, the tendency of teams to perform better at their own ground, comes from familiarity with the stadium. If both teams call the same stadium home, neither has an edge. Therefore, in a derby between groundsharing clubs, home advantage should be zero, and matches between them should be treated as neutral.

A related claim extends this to all matches: that clubs which share a stadium enjoy a weaker home advantage in general, because the ground is never fully "theirs".

Why People Believe It

The myth has an intuitive logic, and there are real reasons it feels convincing.

First, familiarity is the most visible part of home advantage. Players know the pitch dimensions, the surface, the dressing rooms and the sightlines. In a groundshare, both teams train or play there regularly, so this advantage is shared.

Second, groundshare derbies look neutral. The stadium is the same, the city is the same, and travel is irrelevant. To an observer, nothing about the setting seems to favour either side.

Third, the most famous groundshares are in Italy, where city-owned stadiums have long been shared, and Italian derbies are often tense, low-scoring affairs in which neither side appears to dominate. That reinforces the impression that venue plays no role.

Breaking Home Advantage Into Its Parts

To test the myth, it helps to remember that home advantage is not one thing. Research over several decades has pointed to several overlapping components:

• Familiarity with the pitch, surroundings and routine.
• Travel, including fatigue and disruption for the away team.
• Crowd support, including the effect on players' confidence and energy.
• Officiating, where crowd pressure may influence marginal decisions such as fouls, cards and added time.
• Territoriality and psychology, the sense of defending one's own ground.

A groundshare affects these components differently. Some are removed, some are reduced and some are untouched.

What a Groundshare Removes

Familiarity is the component most clearly cancelled. Both clubs know the stadium intimately, so neither gains from knowing the surface, the dimensions or the layout.

Travel is also largely removed in a derby, since both teams are local. Neither side experiences the fatigue of a long journey or an unfamiliar hotel.

These two components are real, which is why the myth contains some truth. If home advantage were entirely about familiarity and travel, a groundshare derby really would be neutral.

What a Groundshare Does Not Remove

The crowd is where the myth begins to break down. In a groundshare derby, one club is designated the home side, and that club typically controls most of the ticket allocation. Its supporters usually occupy the larger share of the stands, its traditional end of the stadium is filled with its own fans, and the matchday experience, from announcements to pre-match displays, is organised around it.

That means the crowd is not neutral. It leans towards the designated home team, sometimes heavily. If crowd support influences players or officials, the designated home side should still benefit.

Officiating pressure follows the same logic. Studies of home advantage have often found that referees' marginal decisions tend to favour home teams, and that this effect weakens when crowds are absent. A groundshare derby with a full stadium still has a crowd weighted towards one side, so any crowd-related refereeing bias is likely to remain in some form.

Psychology is harder to measure, but clubs in groundshares often maintain distinct home identities, with their own branding, end of the stadium and rituals. The sense of "our match" belongs to the designated home side.

What the Data Can and Cannot Show

Testing the myth with data is difficult for several reasons.

Small samples. Groundsharing clubs meet only a few times per season. Even across many decades, the number of league derbies between any single pair is modest by statistical standards, and results are heavily influenced by the relative strength of the two teams in each era.

Strength differences. Over any period, one club may be clearly stronger. Raw home and away records in the derby then mostly reflect that strength gap, not venue effects.

Changing conditions. Ticket allocations, stadium renovations and safety rules change over time, altering the balance of home and away support.

Because of these issues, the most useful approach is not to look for a single headline percentage but to compare like with like. That means comparing each club's derby results as designated home side and as designated away side over the same period, ideally alongside measures of performance such as shots and expected goals rather than results alone. The derby results archive on RubiScore is a practical place to begin assembling that kind of comparison for a particular pair of clubs.

How a Groundshare Derby Differs From a Neutral Venue

It is tempting to treat a groundshare derby as equivalent to a cup final at a neutral stadium. The two situations differ in an important way.

At a true neutral venue, such as a national stadium hosting a final, ticket allocations are usually split between the two clubs by the organiser, and neither side has a recognised home end or matchday identity. Familiarity is often low for both teams, and both may travel.

In a groundshare derby, familiarity is high for both teams rather than low, travel is minimal, and the ticket split is set by which club is hosting rather than divided evenly. The setting therefore removes some home-advantage components that a neutral venue also removes, while preserving the crowd imbalance that a neutral venue is designed to eliminate.

That combination makes groundshare derbies a distinct category. Analysts who pool them with neutral-venue matches risk mixing two different environments, and those who pool them with ordinary home fixtures risk overstating venue effects.

Examples of Groundsharing Clubs

Several well-known groundshares illustrate the different forms the arrangement can take:

• Inter and AC Milan share San Siro, one of Europe's most famous stadiums, and alternate as designated home side in the Derby della Madonnina.
• Roma and Lazio share the Stadio Olimpico in Rome, where the Rome derby is played with each club's supporters traditionally occupying opposite ends.
• Genoa and Sampdoria have long shared the Stadio Luigi Ferraris, home of the Derby della Lanterna.
• Bayern Munich and 1860 Munich shared the Allianz Arena after it opened in 2005, until 1860 left the stadium in 2017.

Each case shares the same core feature: a familiar stadium for both, combined with a crowd that leans towards whichever club is hosting.

What About Non-Derby Matches?

The second version of the myth, that groundsharing clubs have weaker home advantage overall, is less well supported by the logic above. Against other opponents, a groundsharing club still enjoys familiarity, the visiting team still travels, and the crowd is still mostly home supporters.

There may be subtle effects. A stadium that is shared can be less tailored to one club, with neutral decor, shared facilities and a pitch maintained for two fixture lists. Pitch wear from hosting two clubs is a practical concern, especially in winter. But there is no strong reason to expect a large reduction in home advantage against non-local opponents.

The Nuance: Partly True

The myth is partly correct. A groundshare derby removes familiarity and travel, two genuine components of home advantage. In that sense, such matches are closer to neutral than ordinary fixtures.

But the derby does not become fully neutral. The crowd remains weighted towards the designated home side, and with it any influence on players and officials. The best description is that home advantage is reduced rather than cancelled.

The Corrected Takeaway

Instead of "groundshare derbies have no home advantage", a more accurate statement would be:

• Familiarity and travel effects largely disappear in a groundshare derby.
• Crowd-related effects, including any influence on officiating, can remain because the designated home side usually has the larger share of supporters.
• Overall, home advantage in these fixtures is likely to be smaller than in normal matches but not zero.
• Against other opponents, groundsharing clubs should be expected to have a broadly normal home advantage.

For anyone analysing these fixtures, the practical lesson is to record which club was the designated home side, to compare results in both configurations, and to avoid treating a groundshare derby as a neutral-venue match by default.