How Google Maintains Its Search Dominance: Key Insights from a New Study

A recent study from Stanford, MIT, and the University of Pennsylvania sheds light on why Google continues to dominate the search market, holding nearly 90% market share. The research reveals that Google’s advantage isn’t just about superior quality—it’s reinforced by default search agreements, user inattention, and limited exposure to alternatives.

The study finds that when users are required to actively choose a search engine, very few switch away from Google. However, when users experience Bing for two weeks, a significant number update their preferences and continue using it. These findings have major implications for ongoing antitrust discussions and potential regulatory interventions. Here’s a breakdown of the key takeaways from the study.

1. Limited Role of Switching Costs

One common argument is that people stay with Google because switching to another search engine is difficult. However, the study found that when Google users were given an active choice screen, Bing’s market share increased by just 1.1 percentage points—a negligible change. This suggests that switching costs alone do not explain Google’s overwhelming market share.

The small switching rate suggests that eliminating switching costs and inattention would not meaningfully reduce Google’s market share.

Implication:

• Google’s continued dominance cannot be explained by the idea that switching search engines is too difficult for users. Other factors, such as default effects and quality perceptions, play a larger role.

2. User Experience Shifts Preferences

The study tested what happens when users are forced to use Bing for two weeks. A third of these users (33%) decided to keep using Bing even after the experiment ended.

64% of participants who actively decided to keep using Bing reported that it was better than expected, and 59% reported that they had gotten accustomed to using Bing.

When users actually try Bing, their perception of it improves, and some choose to stick with it. Google’s dominance benefits from the fact that most people never meaningfully experience a competitor.

Implication:

• Users tend to stick with Google not because they have tried Bing and rejected it, but because they have never meaningfully experienced it.
• Policies aimed at increasing exposure to alternative search engines could have a bigger impact on competition than simply making switching easier.

3. Google’s Default Agreements Prevent Users from Learning About Alternatives

Many users never experience an alternative search engine because Google is set as the default on Chrome, Android, and many other platforms.

When users’ default search engine was changed from Google to Bing:

• 81% accepted a $10 payment to make that switch.
• After two months, 46% had not switched back—showing persistent inattention as a major factor in market share retention.

Changing defaults can induce learning about unobserved product quality, leading to lasting effects by altering users’ perceptions.

Implication:

• Google’s market share is not just the result of consumers actively preferring it—many users simply never experience an alternative due to its default position.
• This strengthens the argument that Google’s exclusive agreements with device manufacturers and browsers create an artificial advantage.

4. Default Search Agreements Limit Competition

• Google’s dominant market share (about 90%) is not just due to superior quality but also because its position as the default search engine limits users’ exposure to alternatives.
• Policies that increase consumer exposure to Bing (e.g., making Bing the temporary default) reduce Google’s market share more than requiring active choice.

“If Google were prevented from bidding to be the default search engine, Bing could become the default on all browsers. This would increase Bing’s market share by 40 percentage points. However, it would decrease consumer surplus by $70.92 per consumer per year, because a large number of users will now use Bing even though they strongly prefer Google.”

5. Active Choice Screens Have Minimal Impact

In response to regulatory pressure, Google implemented a choice screen for Android users in Europe, where users must pick a search engine when setting up their device. However, the study found that such policies have little impact, increasing Bing’s market share by only 1.3 percentage points.

Choice screens eliminate some frictions but do not address the larger barrier to competition—users’ misperceptions about Bing’s quality.

Implication:

• Simply asking users to choose a search engine at setup is not enough to drive competition.
• To meaningfully challenge Google’s dominance, users must have firsthand experience with alternative search engines.

6. Data Sharing Would Not Significantly Reduce Google’s Market Share

One argument for Google’s market power is that it has far more data, which improves its search results. The study tested this by estimating how much Bing’s performance would improve if it had access to Google’s data. The result? A minimal impact on market share

• Providing Microsoft with Google’s click-and-query data would only slightly improve Bing’s search relevance, increasing its click-through rate from 23.5% to 24.8%.
• This suggests that economies of scale in search data are not a major barrier to competition.

Implication:

• Sharing search data would not significantly level the playing field, because Google’s advantage comes more from default agreements and user experience gaps rather than superior data alone.
• Antitrust remedies focused on data sharing may be less effective than previously assumed.

7. Policy Implications: Increasing Exposure to Alternatives is More Effective

If Google were prevented from paying to be the default search engine, and Bing became the default instead, the study estimates that Bing’s market share would increase by 40 percentage points. However, this would also reduce consumer surplus by $70.92 per user per year, as many users still prefer Google.

A delayed choice screen (where Bing is the initial default, but users must later actively choose) could reduce Google’s market share by 16.7 percentage points without harming consumer welfare.

Implication:

Forced changes in defaults could rebalance the market, but many users would still actively choose Google. A potential compromise is a delayed choice screen, where users try Bing for a period before being required to make a choice.

8. Consumer Preferences Show Asymmetry

• Many users have strong preferences for Google, but a substantial number are weakly attached and would switch for minimal incentives.
• A $1 payment led to a 32% Bing market share, while $10 raised it to 64%, suggesting that a large portion of users are close to indifferent between Google and Bing.

9. Google’s Market Power Is Reinforced by User Expectations

• The study supports the argument that Google’s dominance is not purely merit-based but is sustained by default agreements and user inattention.
• The results suggest that regulatory efforts should focus on exposing users to alternatives rather than just reducing switching costs.

These findings provide empirical evidence relevant to antitrust discussions, particularly in cases addressing Google’s search dominance and default search engine agreements.

Final Thoughts: The Policy Challenge

This study provides strong empirical evidence that Google’s dominance is reinforced by its default agreements, user inattention, and lack of exposure to alternatives. While switching costs are minimal, simply giving users a choice is not enough to drive competition—experience with alternative search engines is key.

For regulators and antitrust authorities, this means:

• Choice screens alone will not solve the issue.
• Forcing Google to share data would have little effect.
• Interventions that expose users to alternative search engines—such as a delayed choice screen—could have a more meaningful impact.

As legal battles over Google’s search dominance continue, this study provides critical insights into the real barriers to competition in web search.

You can read the full document here.

Related Links:

• Google’s Proposed Final Judgment: Addressing Antitrust Concerns
• Antitrust Ruling on Google: Key Transparency Measures for Advertisers Explained
• Google’s Monopoly Power Confirmed in Landmark Antitrust Ruling