Why it exists at all

Bitcoin is crypto's largest asset class, but as a pure store of value most of it sits idle. To use BTC in an Ethereum lending market, you need a form a smart contract can hold. That's wrapped BTC: a 1:1 representation of bitcoin held elsewhere. In practice it's mostly posted as collateral to borrow against — or used for liquidity and yield.

A terminology note: the major variants are wrapped (1:1 backed by real BTC), not synthetic (pegged via collateral, with no BTC locked). The whole market is effectively a wrapped market.

The map: who's who

Four custody models split the field:

• WBTC (federated multisig, BitGo + partner) — the historical number one, still largest by supply, live across Ethereum, major Layer-2s, Solana, Tron and Polygon, and a base collateral tier in Aave, Morpho, Curve and Sky.
• cbBTC (Coinbase, single custodian) — since September 2024, the growth driver, dominant on Coinbase's Layer-2 Base, also on Ethereum and Solana. The trade-off: fully centralized custody.
• tBTC (Threshold, threshold cryptography) — the decentralized alternative: BTC sits with a rotating set of node operators, a majority of whom must co-sign; no single party ever holds the full key. Permissionless redemption is its differentiator.
• FBTC, BTCB, LBTC, cirBTC — FBTC (Mantle orbit), Binance's BTCB (on BSC), Lombard's restaked LBTC, and Circle's new institutional cirBTC with on-chain verifiable reserves, going mainnet in 2026.

Growth — up, with a caveat

The monopoly is broken. Until recently WBTC was effectively unrivaled; today it holds roughly two-fifths of the market, cbBTC about a quarter, Binance's variant about a fifth. The shift was triggered by a 2024 custody controversy, after which Coinbase delisted WBTC and launched cbBTC — since then cbBTC has been the main growth driver, while the rest mostly stagnated.

In USD the wrapped-BTC market peaked near 35 billion in September 2025 and now sits closer to 25 with the BTC price. In BTC units, the float stands at new highs around 300,000 BTC.

The reality check

Now for perspective. Measured against all of Bitcoin, it's tiny: even generously counted — including native staking and every wrapped variant — the share is in the sub-one-percent range of circulating BTC. "Bitcoin DeFi" is real, but a niche.

And the DeFi depth behind it is more fragile than TVL charts suggest. Many protocols subsidized their "total value locked" with token emissions; when emissions dried up and airdrop farmers left, TVL shrank accordingly. The metric that matters isn't parked capital — it's revenue per BTC locked.

The risk stack

Wrapped BTC doesn't just inherit Bitcoin's price; it adds its own risks. The centralized variants (WBTC, cbBTC, FBTC, cirBTC) depend on a custodian — if it fails or miscounts, the backing is at risk. Threshold models like tBTC soften that but swap it for smart-contract and signer risk. Cross-chain transfers add bridge attack surface, and every wrapper carries depeg risk if the 1:1 link breaks. The punchline: much of "Bitcoin DeFi" rests on centralized custodians — the opposite of Bitcoin's own promise.

A methodical bottom line

Separate evidence from interpretation. Evidence: wrapped BTC is the largest wrapped-asset category, it's growing, and cbBTC has moved the market from monopoly to competition. Interpretation: that "Bitcoin is now productive" holds for under one percent of supply — impressive in absolute dollars, small in relative terms. To judge the ecosystem, look at usage and revenue per BTC, not headline parked TVL — and keep the custody stack in view.

FAQ

What is wrapped BTC? A 1:1 token on a smart-contract chain representing bitcoin held elsewhere, so BTC can be used in DeFi (lending, liquidity, yield).

Which variant is largest? WBTC still leads by supply but has lost share to cbBTC (Coinbase), which has grown fastest since 2024 — especially on Base.

How big is Bitcoin DeFi really? Small relative to Bitcoin: even including staking and all wrappers, the share is in the sub-one-percent range of circulating BTC. Real, but niche — and carrying custody, bridge and depeg risk.

This post is an analytical read, not investment advice. Study the Past — Improve your Future. 🥋