Fidelity Rejects Claims Bitcoin Security Weakens After Halvings

TLDR

• Fidelity said Bitcoin security has not weakened despite lower miner rewards after scheduled halving events.
• Bitcoin’s hash rate rose over 8,000% since the 2016 halving, according to Fidelity.
• The April 2024 halving cut Bitcoin’s block reward from 6.25 BTC to 3.125 BTC.
• Fidelity said transaction fees can help support miners as Bitcoin block subsidies continue falling.
• Public Bitcoin miners still face cost pressure and are expanding into AI and computing services.

Fidelity Digital Assets has rejected claims that Bitcoin becomes less secure after each halving, saying the network’s incentives continue to support miners even as block rewards decline.

The asset manager made the argument in its June 2026 report, “Bitcoin’s Programmed Security: Part Two,” written by Fidelity research analyst Daniel Gray. The report follows Fidelity’s March 2024 analysis and responds to concerns that Bitcoin’s fixed supply schedule may weaken miner incentives over time.

Bitcoin halvings reduce the number of new BTC paid to miners roughly every four years. Critics say lower block subsidies could reduce mining revenue and make the network easier to attack unless transaction fees grow enough to replace the lost rewards.

Fidelity Points to Hash Rate Growth

Fidelity said Bitcoin’s security depends on more than block rewards. The report cited hash rate growth, difficulty adjustments, transaction fees, and market incentives as factors that keep miners active and make attacks costly.

Since the 2016 halving, Bitcoin’s hash rate has increased by more than 8,000%, according to Fidelity. Since the 2020 halving, the hash rate has risen 394%, even though miner rewards were reduced during that period.

The April 2024 halving lowered Bitcoin’s block reward from 6.25 BTC to 3.125 BTC. The next halving, expected around 2028, will cut the reward to 1.5625 BTC.

Gray said miner incentives have strengthened in dollar terms as Bitcoin’s price has risen. He wrote that

Difficulty Adjustment Helps Balance Mining

Fidelity also pointed to Bitcoin’s difficulty adjustment as a key part of the network’s security design. The mechanism adjusts mining difficulty every 2,016 blocks, or about every two weeks.

When miners leave the network, difficulty can fall and make it easier for remaining miners to find blocks. When more miners join, difficulty rises and keeps block production near the expected pace.

The report said temporary hash rate declines after halvings have occurred, but they have not led to major security failures. Fidelity argued that the cost of a 51% attack remains much higher than the likely gains from attempting one.

The report also looked beyond 2040, when Bitcoin block subsidies will be much smaller. Fidelity said even in low-subsidy conditions, the economics of attacking Bitcoin remain unfavorable under its assumptions.

Transaction Fees Become More Important

Transaction fees are expected to become a larger part of Bitcoin miner revenue as block rewards shrink. Fidelity said fee demand can act as a long-term bridge for network security.

During the April 2024 halving, fees in one Bitcoin block reached about 12 times the block subsidy. That spike was linked partly to the launch of the Runes protocol, which increased demand for block space.

Fidelity did not say every block will produce fee revenue at that level. Instead, the report used the event to show that users can pay high fees when demand for Bitcoin block space rises.

Average daily miner revenue has also increased across cycles. Fidelity said miner revenue moved from about $26,300 during Bitcoin’s first halving cycle to more than $40.2 million today.

Public Miners Still Face Pressure

Fidelity’s long-term view does not remove current pressure on public Bitcoin miners. Mining firms are facing lower rewards, higher costs, and stronger competition after the latest halving.

Some miners have moved into artificial intelligence and high-performance computing to use their power infrastructure and data centers for non-mining revenue. VanEck, as we reported, estimated that listed miners may need up to $50 billion in capital to fully build out AI infrastructure.

Fidelity’s report separates Bitcoin’s network security from the business pressure facing individual miners. The firm said Bitcoin’s design still gives miners reasons to secure the network, while weaker operators may need to cut costs, raise capital, or diversify revenue.