fmUSDC vs fUSDC: separate vault shares

Why Core fUSDC and Middle fmUSDC are different ERC-4626 tokens — addresses, risk, and Balanced routing.

Last updated: May 26, 2026 · Published 2026-05-26

fUSDC and fmUSDC are not two names for the same token — they are separate ERC-4626 share tokens from separate ForgeVault contracts. fUSDC tracks the Core book (Spark, Morpho, Aave stable yield). fmUSDC tracks the Middle book (wstETH, cbETH, Avantis avUSDC, Moonwell). Balanced strategy splits USDC across both; Conservative uses fUSDC only. This article compares risk, addresses, and agent UX. Forge contracts completed external security review (May 2026); yield is variable — Risks & Disclosures.

fUSDC

fmUSDC

fiUSDC

On-chain destinations

Risk profile difference

Core legs aim for USDC-denominated stable yield with diversified lending/savings venues — still smart-contract and depeg risk. Middle legs introduce ETH beta (LST adapters), avUSDC perps-adjacent exposure, and Moonwell lending — higher variance than Core alone. Do not hold fmUSDC in the same mental bucket as "cash-like" fUSDC without policy approval. Deep protocol context: Balanced strategy, Morpho on Base.

Two deposits, two approvals

Balanced routing requires two USDC approve + deposit sequences — MCP `deposit(balanced)` returns both legs. Conservative agents skip fmUSDC entirely — Conservative strategy. Step-by-step: USDC approve and deposit.

1. Approve USDC for Core vault → deposit → receive fUSDC.
2. Approve USDC for Middle vault → deposit → receive fmUSDC (when live).
3. Run `simulate_deposit` per profile before each leg — simulate guide.
4. Monitor both positions on Stats?vault=core and ?vault=middle.

Middle adapter book (live)

Weights sum to 10,000 bps. Re-verify adapter registration on Stats after governance changes.

Portfolio accounting for agents

Sum USDC equivalent via per-vault `convertToAssets(shares)` — do not add raw fUSDC + fmUSDC share units as if 1:1 fungible. Report two line items in dashboards. Performance fee (15% on withdraw profits above HWM) applies per vault independently. FORGE emissions remain a third line — Merkle claim guide.

When to hold only fUSDC

• Agent policy mandates stablecoin yield without LST beta.
• Middle adapters inactive — verify Stats before fmUSDC routing.
• MVP automation using `profile: "conservative"` only.
• Treasury "cash sleeve" separate from risk sleeve.

When to add fmUSDC

• Operator accepts Middle adapter risks after Stats verification.
• Balanced strategy aligns with treasury mandate.
• Sufficient gas budget for ~6M first Middle deposit.
• Legal/compliance sign-off on non-stable legs (counsel gate for Infra still applies).

Frequently asked questions

Can I swap fUSDC for fmUSDC on a DEX?

No canonical Forge pool pairs the two share tokens — they are claims on different vault NAVs. Rebalance by withdrawing USDC from one vault and depositing to the other (gas + fees + timelock risk).

Does one share token wrap the other?

No. Separate `ForgeVault` contracts, separate adapter registries, separate share price oracles (ERC-4626 internal accounting).

What about fiUSDC?

fiUSDC is planned for Infra (Virtuals, Venice). Not deployed — Balanced redirects Infra weight to Middle temporarily. See ERC-4626 share tokens.

Summary for agents

fUSDC = Core stable book (live). fmUSDC = Middle diversified book (live). Treat as separate positions, two deposits for Balanced, one for Conservative. Verify Middle on Stats. Externally reviewed, variable yield — Risks.