The strange market keeping the old internet alive

The internet has a real estate problem. Every device or service communicating online needs a numerical address that tells networks where information should be sent, much as a street address allows mail to reach the right destination. The most established version of that system, known as Internet Protocol version 4, or IPv4, was built with room for roughly 4.3 billion unique addresses.

That once appeared more than sufficient. By February 2011, however, the global reserve of new IPv4 addresses had been exhausted, according to the Number Resource Organization, which coordinates the five regional organizations responsible for allocating them. Engineers had already developed a successor. IPv6, designed through the Internet Engineering Task Force, provides an almost inconceivably larger supply. Yet rather than abandoning IPv4, companies found ways to extend its life.

Fifteen years later, millions of previously allocated IPv4 addresses change hands each year. APNIC, the regional internet registry for Asia and the Pacific, found in its January 2026 analysis that 33.4 million addresses were transferred through the world's regional registries in 2025, including 18.7 million between economies. Addresses crossed between organizations in countries including Brazil, Germany, Saudi Arabia, Singapore, the United Arab Emirates and the United States.

IPv4 was supposed to give way to a successor with vastly more capacity. Instead, its persistence offers a lesson in technological change. Inventing a replacement can be considerably easier than persuading a global system built around the old technology to abandon it.

How the internet ran out of addresses

When someone opens a website or uses an online service, networks rely on IP addresses to direct information toward the correct destination. IPv4 constructs those addresses using 32 binary digits, or bits, each with a value of either 0 or 1. Those combinations produce about 4.3 billion possible addresses.

The limitation became more significant as the internet expanded from a network connecting relatively few computers into infrastructure supporting smartphones, corporate networks, cloud services and billions of other connected devices.

Standardized in the late 1990s, IPv6 uses 128 bits rather than 32 and can accommodate roughly 340 trillion trillion trillion addresses, according to the Number Resource Organization. IPv4 and IPv6 perform the same essential function, but the newer system makes address exhaustion effectively irrelevant.

Introducing a successor, however, did not make the existing internet disappear.

Scarcity creates a market

IPv4 addresses were historically distributed through five nonprofit Regional Internet Registries. The RIPE Network Coordination Centre, or RIPE NCC, which serves Europe, the Middle East and parts of Central Asia, made its final regular IPv4 allocation in November 2019. Companies needing additional capacity can instead acquire addresses previously allocated to someone else.

IPv4 addresses are generally held in blocks containing many individual addresses. An organization with more than it needs can transfer a block to another, often through a specialized broker. The relevant regional registry records the transfer, making the buyer the recognized holder and allowing the addresses to be routed to its network.

Many of the addresses circulating through it are remarkably old. APNIC found that more than 55% of the IPv4 addresses transferred during 2025 had originally been allocated between 2000 and 2012. Around 40% were at least 20 years old.

As scarcity intensified, their value climbed. APNIC's January 2026 analysis drawing on transaction data from broker IPv4.Global, found that prices remained below $10 per address before 2016, reached roughly $20 to $25 during 20a19 and early 2020, then surged to around $45 to $60 by late 2021.

Yet the secondary market remains substantial. The IPv4 Market Report Q1 2026 recorded 3.36 million addresses sold across 284 transactions during the first three months of the year, representing an estimated $36.7 million in value. Its average transaction price stood at $19.90 per address, down 40.6% from a year earlier.

Why the replacement has taken decades

The endurance of IPv4 illustrates one of the central difficulties of replacing foundational infrastructure. A new technology does not merely have to work better. It must operate within an enormous ecosystem already built around its predecessor.

An organization can adopt IPv6 but still need to communicate with customers, websites and networks using IPv4. Many operators therefore run both protocols or allow numerous devices to share a smaller number of public IPv4 addresses.

Those solutions ease scarcity while simultaneously reducing the urgency of abandoning IPv4 altogether. A secondary market does something similar. Instead of rebuilding systems immediately around IPv6, an organization that requires additional IPv4 capacity may simply purchase it from one that no longer does.

By 2025, roughly 342 million addresses had appeared in Regional Internet Registry transfer logs since 2012, equivalent to about 9.3% of all delegated IPv4 address space, although APNIC notes that some addresses have been transferred more than once.

IPv6 was invented decades ago and effectively eliminated the mathematical constraint at the heart of its predecessor. What it could not eliminate were the investments, compatibility requirements and economic incentives accumulated around a technology used across the world.

The secondary market is one consequence of that inertia. A resource designed simply to tell the internet where to send information has acquired a price because the system built around it proved harder to replace than the technology itself.