> ## Documentation Index
> Fetch the complete documentation index at: https://docs.ostium.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Fund Your Account

> Get USDC on Arbitrum to start trading. Your funds stay in your wallet; the Ostium smart contracts lock margin when you open a trade and return it when you close.

## Overview

Trading on Ostium requires USDC on <Tooltip tip="An Ethereum Layer 2 network with sub-second finality and low gas costs.">Arbitrum</Tooltip> 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 <Tooltip tip="The collateral locked for a position. Returned (plus or minus PnL) when you close.">margin</Tooltip>. 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.

| Method                     | Speed        | Fees                 | Best for                      |
| -------------------------- | ------------ | -------------------- | ----------------------------- |
| Built-in on-ramp (Fun.xyz) | \~1 minute   | Small gas + swap fee | New users, multi-chain assets |
| Send USDC on Arbitrum      | Instant      | Arbitrum gas only    | Already on Arbitrum           |
| CEX withdrawal             | 5–30 minutes | Exchange fee         | Binance, Coinbase users       |
| Bridge from Ethereum       | 1–10 minutes | Gas + bridge fee     | Existing ETH mainnet holders  |

## 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.

<Steps>
  <Step title="Click Fund Account in the Ostium app">
    Open the Ostium app and click the Fund Account button.
  </Step>

  <Step title="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.
  </Step>

  <Step title="Copy your unique deposit address">
    The interface generates a one-time deposit address. Copy it.
  </Step>

  <Step title="Send your token to that address">
    Transfer from your external wallet to the copied address.
  </Step>

  <Step title="USDC arrives in your connected wallet">
    Within 1–2 minutes, USDC lands in your Arbitrum wallet. You're ready to trade.
  </Step>
</Steps>

The credited amount reflects your deposit minus swap and bridge fees. Onchain gas fees apply on your source network; check the estimate before sending.

<Note>
  Each transaction generates a unique address. Do not reuse addresses across multiple transactions. Always copy the fresh address shown.
</Note>

## 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.

<Steps>
  <Step title="Copy your connected wallet address from your Ostium profile">
    Find your wallet address in the Ostium app or your wallet extension.
  </Step>

  <Step title="Send USDC on Arbitrum to that address">
    Initiate a USDC transfer on Arbitrum from your other wallet.
  </Step>

  <Step title="Balance updates instantly">
    Once the transaction confirms onchain, your wallet balance reflects the new USDC. Ostium reads your wallet balance directly.
  </Step>
</Steps>

## CEX Withdrawal (Binance, Coinbase, etc.)

Most major exchanges support USDC withdrawal directly to Arbitrum.

<Steps>
  <Step title="Log into your exchange and navigate to USDC withdrawal">
    Go to the withdraw or send section for USDC.
  </Step>

  <Step title="Select Arbitrum as the destination network">
    Choose Arbitrum from the network dropdown. This is critical; do not select Ethereum or another chain.
  </Step>

  <Step title="Paste your wallet address and confirm">
    Enter your connected wallet address and complete the withdrawal.
  </Step>

  <Step title="USDC arrives in your wallet within minutes">
    Exchange processing takes 5–30 minutes depending on the platform.
  </Step>
</Steps>

Exchange fees vary but are typically 0–5 USDC.

## Bridge from Ethereum Mainnet

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

<Steps>
  <Step title="Open a bridge interface">
    Go to a bridge like [Stargate](https://stargate.finance), [Across](https://across.to), or another provider.
  </Step>

  <Step title="Configure the bridge">
    Set USDC as the token, Ethereum as the source, and Arbitrum as the destination. Enter your wallet address as the recipient.
  </Step>

  <Step title="Approve and confirm">
    Confirm the transaction in your wallet. Allow 1–10 minutes for the bridge to finalize.
  </Step>

  <Step title="USDC lands in your Arbitrum wallet">
    Once complete, your Arbitrum wallet balance updates and you're ready to trade.
  </Step>
</Steps>

Bridge fees vary by provider, typically \$1–10.

## Troubleshooting

**USDC not showing in Ostium after transfer?** Check the transaction on [Arbiscan](https://arbiscan.io) 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.

<Warning>
  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.
</Warning>

## FAQ

<Accordion title="Why don't I deposit into Ostium directly?">
  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.
</Accordion>

<Accordion title="Can I fund from any chain?">
  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.
</Accordion>

<Accordion title="How long does funding take?">
  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.
</Accordion>

<Accordion title="What happens to my USDC when I'm not trading?">
  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.
</Accordion>

## What to Read Next

* **[Connect Your Account](/traders/getting-started/connect-account)** — Set up email or Web3 wallet login.
* **[Opening a Trade](/traders/trading/opening-a-trade)** — Start trading with your funded wallet.