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Overview

Trading on Ostium requires USDC on in your connected wallet. There is no separate Ostium balance or deposit step; your USDC sits in your wallet until you open a trade. When you open a trade, the Ostium smart contracts lock the required . When you close that trade, the margin (plus or minus your PnL) is returned to your wallet. If you already have USDC on Arbitrum, you’re ready to trade. If not, there are several ways to get it there.

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Built-In On-Ramp

The Ostium app integrates a built-in on-ramp provided by third-party Fun.xyz that lets you swap tokens from any supported chain (Ethereum, Base, Polygon, Solana, etc.) into USDC on Arbitrum. Fun.xyz handles the swap and bridge automatically; Ostium itself does not operate any on-ramp service.
1

Click Fund Account in the Ostium app

Open the Ostium app and click the Fund Account button.
2

Select your source token and chain

Choose the token you want to convert (ETH, USDT, USDC on another chain, etc.) and the chain it’s on.
3

Copy your unique deposit address

The interface generates a one-time deposit address. Copy it.
4

Send your token to that address

Transfer from your external wallet to the copied address.
5

USDC arrives in your connected wallet

Within 1–2 minutes, USDC lands in your Arbitrum wallet. You’re ready to trade.
The credited amount reflects your deposit minus swap and bridge fees. Onchain gas fees apply on your source network; check the estimate before sending.
Each transaction generates a unique address. Do not reuse addresses across multiple transactions. Always copy the fresh address shown.

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Send USDC Directly

If you already hold USDC on Arbitrum in another wallet, send it to your connected wallet address. This is the fastest option with the lowest fees.
1

Copy your connected wallet address from your Ostium profile

Find your wallet address in the Ostium app or your wallet extension.
2

Send USDC on Arbitrum to that address

Initiate a USDC transfer on Arbitrum from your other wallet.
3

Balance updates instantly

Once the transaction confirms onchain, your wallet balance reflects the new USDC. Ostium reads your wallet balance directly.

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CEX Withdrawal (Binance, Coinbase, etc.)

Most major exchanges support USDC withdrawal directly to Arbitrum.
1

Log into your exchange and navigate to USDC withdrawal

Go to the withdraw or send section for USDC.
2

Select Arbitrum as the destination network

Choose Arbitrum from the network dropdown. This is critical; do not select Ethereum or another chain.
3

Paste your wallet address and confirm

Enter your connected wallet address and complete the withdrawal.
4

USDC arrives in your wallet within minutes

Exchange processing takes 5–30 minutes depending on the platform.
Exchange fees vary but are typically 0–5 USDC.

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Bridge from Ethereum Mainnet

If you hold USDC on Ethereum, bridge it to Arbitrum using Stargate, Across, or another bridge provider.
1

Open a bridge interface

Go to a bridge like Stargate, Across, or another provider.
2

Configure the bridge

Set USDC as the token, Ethereum as the source, and Arbitrum as the destination. Enter your wallet address as the recipient.
3

Approve and confirm

Confirm the transaction in your wallet. Allow 1–10 minutes for the bridge to finalize.
4

USDC lands in your Arbitrum wallet

Once complete, your Arbitrum wallet balance updates and you’re ready to trade.
Bridge fees vary by provider, typically $1–10.

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Troubleshooting

USDC not showing in Ostium after transfer? Check the transaction on Arbiscan using your wallet address. If the transfer confirmed onchain, refresh the Ostium app or wait a few minutes for the UI to sync. Sent tokens to the wrong chain? Funds sent to non-Arbitrum networks cannot be recovered through Ostium. Contact the bridge or exchange support for help. How much USDC do I need? There is no minimum; your required amount depends on the collateral you use per trade.
Only send USDC on Arbitrum to your wallet. Sending other tokens (USDT, WETH, etc.) or using a different chain (Ethereum mainnet, Solana, etc.) may result in permanent loss of funds. Always verify the network before sending.

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FAQ

Ostium is non-custodial. Your USDC sits in your connected wallet until you open a trade; margin is then locked in the protocol contracts for the duration of the position and returned (adjusted for PnL and fees) when you close. Keys and approvals remain under your control throughout.
Yes, via the built-in on-ramp or a manual bridge. The on-ramp supports Ethereum, Base, Polygon, Solana, and others. For unsupported chains, bridge to Arbitrum first using a third-party provider.
Direct USDC on Arbitrum: instant. Built-in on-ramp: 1–2 minutes. Bridges: 1–10 minutes. CEX withdrawals: 5–30 minutes depending on the exchange.
Nothing. It sits in your wallet untouched. The Ostium smart contracts are permitted to interact with your USDC only when you open or close a trade.