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Using the Exchange

USDT / USDC Stablecoin Exchange

Open Mandi includes a built-in exchange where you can swap between USDT and USDC. Unlike most exchanges that fix the rate at 1:1, our rate is determined by the free market — by the actual buying and selling activity of traders on the platform.

What is the Stablecoin Exchange?

The stablecoin exchange is a marketplace within Open Mandi where you can trade USDT for USDC and vice versa. It has its own order book, just like the gold and silver futures markets.

This means the price you get depends on what other traders are offering. It's a real market with real price discovery, even for two currencies that are both designed to be worth $1.

Why Exchange Between USDT and USDC?

There are several reasons you might want to swap stablecoins:

  • You deposited USDT but a futures market you want to trade requires USDC as margin, or vice versa
  • You want to take advantage of a price difference between the two
  • You want to diversify your holdings across both stablecoins
  • You want to learn how order books and market-driven pricing work in a low-stakes environment

How the Exchange Rate is Determined

The exchange rate between USDT and USDC on Open Mandi is not fixed. It's determined entirely by supply and demand through the order book.

Here's a simplified example:

  • Alice wants to sell 1 USDT for 1.002 USDC (she's asking for slightly more than 1:1)
  • Bob wants to buy 1 USDT for 0.998 USDC (he's offering slightly less than 1:1)
  • The spread (gap) between the best ask and best bid is 0.004 USDC
  • When someone places a market order, they'll be matched with the best available price on the other side

Understanding the Order Book

The order book shows two sides:

  • Bids (buy orders) — people who want to buy USDT with USDC. These are sorted from highest to lowest price. The highest bid is what buyers are currently willing to pay.
  • Asks (sell orders) — people who want to sell USDT for USDC. These are sorted from lowest to highest price. The lowest ask is the cheapest price available.

The mid-market price is the average of the best bid and best ask. This is often used as a reference for the "current" exchange rate.

Placing an Exchange Order

You have two options when exchanging stablecoins:

  • Limit order — you specify the exact rate you want. Your order sits on the order book until someone matches it. You might get a better rate but it might take longer (or never fill if your price is too far from the market).
  • Market order — you accept the best available rate right now. Your order is filled immediately at whatever price is available on the other side of the book.

Why Rates May Differ from 1:1

Even though both USDT and USDC are designed to be worth $1, their exchange rate on Open Mandi can deviate from 1:1 for several reasons:

  • Supply and demand — if more people want to sell USDT than buy it, the price drops below 1:1
  • Liquidity — with a smaller number of participants (as on an academic exchange), prices can be more volatile
  • Market sentiment — traders' preferences between the two stablecoins can shift the rate

This is actually one of the most interesting educational aspects of Spikey Coins — you get to see firsthand how market dynamics affect price, even for assets that should theoretically be identical in value.