The Economics of Bank Mergers and Consolidation

Why the number of banks keeps shrinking, and what merging into fewer, larger banks means for customers.

The number of banks in the United States has fallen substantially over the past few decades, even as the total amount of money held in banks has grown enormously. This trend, driven largely by bank mergers - one bank acquiring or combining with another - reshapes the banking landscape customers actually interact with, often in ways that aren’t immediately obvious.

Why banks want to merge

Combining two banks into one lets the resulting institution spread its fixed costs - technology systems, compliance staff, marketing, and executive management - across a larger base of customers and deposits, a case of economies of scale where per-customer cost falls as the institution grows larger. A larger combined bank can also offer a wider range of products, absorb regulatory compliance costs more easily (regulation has grown significantly more complex and expensive since the 2008 financial crisis, covered in the economic history module), and compete more effectively against the largest national banks.

What happens to branches afterward

Two branches becoming one

When two banks merge and both happen to have a branch on the same street in the same town, the combined bank rarely keeps both open - maintaining two nearby branches duplicates rent, staffing, and operating costs without meaningfully improving service to customers who could easily use either one. A predictable wave of **branch closure** typically follows a merger, concentrated in areas where the merging banks' branch networks overlapped most. This can leave some communities, particularly in areas that already had fewer branches, with noticeably less convenient in-person banking access than before.

Market concentration and its tradeoffs

As mergers continue, market concentration - how much of a market’s total activity is controlled by a small number of firms - has risen in banking, with a shrinking number of very large institutions holding a growing share of total deposits. Regulators review proposed mergers specifically to assess this effect, since higher concentration can reduce competitive pressure on fees and interest rates in markets where a merger would leave customers with meaningfully fewer alternative banks to choose from.

Who tends to benefit, and who doesn’t

Shareholders of merging banks often benefit from the resulting cost savings and improved competitive position, and customers in areas with continued strong bank competition may see little practical difference. Customers in communities that lose a nearby branch, particularly those less comfortable with digital-only banking, or small businesses that relied on a personal relationship with local bank staff for loan decisions, can experience a genuine reduction in service quality that the aggregate efficiency gains from a merger don’t fully offset for them individually.

Key takeaways

Bank mergers let combined institutions spread fixed costs like technology and compliance across a larger customer base.
Overlapping branches are a common target for closure after a merger, since maintaining both duplicates costs.
Rising market concentration in banking can reduce competitive pressure on fees and rates in some local markets.
Regulators review mergers specifically to weigh efficiency gains against reduced customer choice.
Merger benefits and costs are unevenly distributed, with some customers losing convenient local access even as others see little change.