ポルカドット (DOT) トケノミクス

Polkadot’s native token, DOT, is the central utility and governance asset of the network. Its economic model is designed to secure the relay chain, facilitate the allocation of network resources (coretime), and enable decentralized governance. As of April 14, 2024, the total supply of DOT was approximately 1.43 billion, having grown from an initial genesis supply of 1.00 billion.

Issuance Mechanism

Polkadot historically utilized a variable inflation model, but recent governance decisions have shifted the network toward a more fixed issuance structure.

• Historical Model: Initially, DOT had a 10% year-on-year token issuance rate. This was designed to reward stakers and fund the treasury. The distribution of these rewards was dependent on the "system staking rate" compared to an "ideal staking rate" (typically between 45% and 75%). If the actual staking rate diverged from the ideal, a portion of the inflation was diverted to the treasury.
• Current Fixed Issuance: In 2024, the network transitioned to a fixed issuance rate of 120 million DOT per year. This change makes DOT disinflationary, as the fixed amount represents a decreasing percentage of the total supply over time.
• Reward Distribution: Of the 120 million annual DOT issuance, approximately 100 million DOT is allocated for staking rewards, with the remainder funding the annual treasury budget.
• Burn Mechanism: To offset inflation, Polkadot employs a burn mechanism where 1% of the available treasury funds are burned at the end of every 24-day spend period. Additionally, 100% of transaction fees and a portion of validator slashing penalties are directed to the treasury, where they may eventually be burned.

Allocation Mechanism

The initial allocation of DOT was established through public and private sales, with subsequent distribution occurring through network incentives and grant programs.

• Initial Distribution: Approximately 22.40% of the initial total token supply (224 million DOT) was sold in a public sale at an average price of $0.288 per token.
• Current Concentration: As of April 14, 2024, the top 10 wallet addresses held approximately 21.05% of the total supply (301.60 million DOT). Major identified holders include Binance (~6.20%), the Polkadot Treasury (~2.61%), and Kraken (~2.45%).
• Grant Programs: The Web3 Foundation’s Grants Program has funded over 600 projects since 2018. A recent initiative, "Decentralized Futures," was earmarked to distribute approximately 5.00 million DOT (0.36% of the total supply) to support ecosystem growth.

Usage and Incentive Mechanism

DOT serves three primary functions: governance, staking, and resource allocation.

Staking and Security

Polkadot uses a Nominated Proof-of-Stake (NPoS) consensus mechanism.

• Validators: Users can run validator nodes to secure the network. They earn rewards based on "Era Points," which are awarded for "payable actions" such as issuing validity statements for parachain blocks or producing blocks on the Relay Chain.
• Nominators: Tokenholders can delegate their DOT to validators to earn a portion of the staking rewards.
• Slashing: To ensure security, validators (and their nominators) are "slashed" or fined if they behave maliciously or experience significant downtime.

Governance

The network is governed by DOT holders through the OpenGov system.

• Proposals: Any tokenholder can submit a proposal by providing a "submission deposit" of one DOT.
• Voting: Users can vote for or against proposals. Voting weight can be increased through "conviction voting," where users lock their DOT for longer periods to multiply their voting power.
• Delegation: Tokenholders can delegate their voting power to other accounts on a per-track basis.

Resource Allocation (Coretime)

Polkadot 2.0 introduced Agile Coretime, transforming how parachains access the network's processing power.

• Bulk Coretime: Purchased via on-chain sales for long-term use.
• Instantaneous Coretime: A pay-as-you-go model for projects needing immediate, short-term access.
• Parathreads: These "on-demand" parachains pay a fixed fee in DOT for periodic block validation rather than leasing a dedicated slot.

Locking Mechanism and Unlocking Time

Locking is a fundamental part of Polkadot’s security and resource allocation strategy.

Unlocking and 2025 Roadmap

Historically, the unbonding period for staked DOT has been 28 days. However, the Polkadot 2025 Roadmap includes a "Fast Unlocking" feature designed to reduce the waiting time for DOT unlocking to improve user experience. For parachain leases, the bonded DOT is automatically unlocked and returned to the original bidders or crowdloan contributors at the end of the 96-week lease period. Significant unlocking events are scheduled through May 2026 as early parachain leases expire.