Index tokens

An index token is an ERC-20 backed by a basket of 2 to 20 tokens it holds: tokenized stocks, crypto tokens, or a mix. Buying it through its own pool mints new shares against the basket, selling it burns shares and pays out of the basket, and any holder can redeem shares for the basket itself at any time.

Rolling out in stages

Index tokens open one chain at a time (Base and Robinhood Chain), to designated wallets first.

Creating an index

On the Create an Index card you pick a name, a ticker, a chain, the basket and its weights, how the basket rebalances (Rebalancing), the index fee (0.25 % to 1.00 % of every trade) and your first buy. One transaction deploys the index, opens its pools and makes your first buy.

Two rules apply, and the card states both before you sign:

Rule	Why
$100 minimum first buy. Creating an index takes a first buy of at least $100 of the basket, minted to you as the index token.	It stops people grabbing tickers for free.
Your own tokens are locked for 24 hours. The index tokens you hold can't be sold, redeemed or sent until 24 hours after creation. Everyone else trades and redeems as usual.	You have real money in your index for its first day.

While your lock runs, Bankr's sell, redeem and send screens show Locked until the time it ends. Creation also buys $1 of the basket and burns it, so an index is never empty.

Trading

• Buying and selling go through the index's own pools (the index against USDC or USDG, and against WETH). A buy purchases every token in the basket at its weight; a sell sells them. The index fee applies to both.
• No size limit. There is no cap on how much of an index can be minted and no limit on a trade's size. What bounds a trade is price: every token's leg must fill within a set band of its reference price, so a trade larger than a pool's depth can take simply doesn't fill, and nothing is lost but gas.
• Stock indexes trade at any hour. In the US market session a stock is priced by its Chainlink feed or a Bankr-signed quote. Before and after the session and overnight, Sunday 8 pm to Friday 8 pm ET, it uses signed 24-hour-market quotes. On weekends and holidays it uses a 30-minute average of the stock's own on-chain pools, computed by both of Bankr's price keys. Outside the session each leg fills within the stock's off-hours price band. A trade waits only while none of these prices is fresh, and there is no off-hours size limit. The exception is a stock whose pools are too thin for that weekend average and that has no 24-hour-market quote yet: it is marked "Trades during NYSE hours only", and an index holding it trades only in the US market session (redeeming for the basket always works).
• Trading pauses, while redeeming keeps working, when:
  • a token in the basket is paused by its issuer, or its price isn't fresh;
  • Bankr's guardian pauses buys or sells;
  • a retired token the index still holds is worth more than dust: sells through the pool close (buys stay open);
  • a retired token has no usable price: buys and sells wait;
  • a token's balance in the index changed unexpectedly and is under review: buys wait, sells keep working.

Fees

Every buy and sell through an index's pools pays its index fee, set at creation and never changed. Bankr keeps 40 % of it; the creator decides how the rest splits between themselves and the index's holders. Each token's own pool fee and price impact are extra. Redeeming for the basket is fee-free.

Holder fee. The holders' part of the fee stays in the basket for holders. It isn't paid out at once: each trade's share starts at the next full hour and is released into the backing of every index token evenly over the following 24 hours. Whoever holds while it's released receives it in proportion to what they hold — the trader included, if they keep holding. Buying and leaving again within the hour receives none of the holder fee from trades in that same hour; it does share in earlier trades' release while it holds.

• The released amount goes to whoever holds during the 24 hours, including people who buy after the trade.
• Large sells leave their holder fee to the holders of the next day; redeeming avoids it. A seller holding almost all of an index is offered Redeem instead of the sale.
• After a very large sale the value per index token can rise quickly at first, because the same dollars are released each hour into a smaller pool.

The Trade page shows Backing per token: what one index token redeems for now. While a holder fee is still being released it adds the dollars being released over the next 24 hours, and what the backing per token would be once everything is released if no one trades.

Rebalancing

Every index has one of three rebalancing modes, chosen when it is created:

Mode	What happens
Off	Nothing is ever traded; the weights drift with prices.
Manual	The creator (the index's rebalancer) proposes new weights, one rebalance at a time: a new one as soon as the last one ended or was cancelled.
Auto	A rule stored on-chain brings the basket back to its own target weights: every month, or once any weight drifts more than a set percentage from its target (10 % to 200 % of that target).

The Create card picks a default from the basket: Auto every month, or Auto at a 50 % drift once the basket holds a memecoin priced by Bankr-signed prices. A token that can't be auctioned yet, because it has no second independent price source, forces Off, and the card names it. Switching to Off later is instant and cancels a running rebalance. Switching to Manual or Auto takes effect 48 hours after it is scheduled. To move from Auto to Manual, switch to Off first and then schedule Manual (the Bankr app does this by default): while the switch waits, Auto stays on, and an Auto rebalance proposed then runs its course (up to 16 days) before the creator can propose one. Going Off cancels a running Auto rebalance.

Notice. Every rebalance is announced 48 hours before it starts, so a holder who disagrees with the new weights can leave first. Selling pays the normal index fee at every point of a rebalance; redeeming for the basket is fee-free and works throughout.

Public auctions. After the notice the basket trades toward its targets in Dutch auctions that anyone can fill. Each auction offers a slice of one overweight token for one underweight token:

• The price starts a little above the reference price and falls over 30 to 60 minutes to a floor it never goes below.
• Fillers compete to fill it, and a fill can be partial.
• Bankr's backstop may bid at any point of an auction, like any filler, at the auction's price and never below its floor. It keeps a fee of at most 0.20 % of the fill (never above 0.50 %, a limit in its code) and only out of what its own trade returns above that price; the index receives the rest.
• An auction that mostly doesn't fill backs off and comes back smaller.
• A rebalance runs for at most 14 days. Whatever has filled by then stays, and the old targets remain for the rest.

Limits. The limits keep every rebalance small and slow:

• Each auction is at most a small share of the basket and of the thinner pool's depth.
• An index trades at most 5 % of its value in any 24 hours.
• Each token has a daily auction limit shared by every index that holds it.
• Each rebalance has a loss budget of 1 % of the basket, for every index. A rebalance that reaches it stops. The budget is net of pool fees: it counts what auction fills give up against the price, but not the trading fees of the pools the fillers route through, so a rebalance's total cost can run above 1 %. The index page shows what rebalancing has cost over the last 30 days and since launch, on the same net measure, and Bankr is alerted when an index's auctions cost more than 2 % in 30 days.

Prices. Auctions read only prices that two independent keys stand behind: a Chainlink feed, or a price that both Bankr's signer and its co-signer sign.

• They run at any hour, on the same in-session, 24-hour-market and weekend-average prices as trading.
• Outside the session the floor is wider and the slices are smaller.
• A weekend auction fills only while the pools agree with the last two-key price within 3 %, or have moved in the index's favour.
• Before starting an auction the contract checks the token's pools against the reference price, and every fill must also clear the floor against the pools' current price.
• No auction price ever enters a buy, sell or redeem of the index: those stay strictly pro rata to the basket.

Auctions switch on separately from trading, on both chains together. Until then a rebalance's notice runs but no auction starts. To fill auctions yourself, see Index auctions for fillers.

Redeeming

Redeem any amount of an index for your share of every token in its basket. It runs on the index contract itself, works without Bankr, is open in every region and can't be paused. A stock basket pays out the tokenized stocks.

• A token whose issuer has paused it is held for you as a claim, which you collect once it trades again.
• If the index can't read or verify its balance of one token, a redeem that includes it fails. You can give up your share of that token and redeem the rest, or try again later.
• An index's creator can't redeem their own index tokens in the first 24 hours (see "Creating an index").

To pair a new token launch with an index, see Index-paired launches.