Managed stock indexes with no keeper to trust

Arca is a family of onchain stock indexes on Robinhood Chain. Each index is a single ERC-20 token, backed one-to-one by a basket of tokenized stocks locked in a vault contract. An autonomous agent runs the basket — rotating weights on a fixed schedule — yet it acts only inside guardrails the contract enforces on its own.

The design draws a line traditional funds never can: management and custody are separate powers. The agent sets weights. The contract holds the assets. Neither can reach into the other's lane.

Why this exists

Every managed fund rests on one quiet assumption: the manager won't touch your money. Custody lives with people and processes you can't inspect, and redemption runs on their timeline, not yours.

• Fully backed, provably. Token supply can never exceed what the vault holds — an invariant enforced on every mint, redeem, and rebalance, not a monthly attestation.
• Redeemable anytime, in-kind. Burn the token and receive every underlying stock in a single transaction. No queue, no approval, and no admin can pause it.
• Managed in the open. Every rebalance lands as a public transaction with its rationale attached. You read why, not just what.

The loop

Mint — deposit the basket, receive the index token. Manage — the agent rotates weights within fixed rails (whitelist, slippage cap, turnover cap, cooldown). Redeem— burn the token, take the stocks back. That's the entire product; every arrow in it is a transaction anyone can verify.