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2.2.7 flexUSD

November 29, 2021

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flexUSD is the first stablecoin that pays holders interest on-chain, every 8 hours. This means regardless of whether flexUSD is sitting in your cold-storage or hot wallet you still earn interest.


Why flexUSD differs from other stablecoins

Other stablecoin issuers pay holders zero interest. To earn yield or interest on your stablecoins you need to put them to work by lending them directly to a third party platform, yield farming or using the stablecoins as collateral to trade derivatives products.


Who would use flexUSD?

flexUSD can be used by everyone who wants to earn passive income:

  • Individuals or companies who want to earn yield passively.
  • Individuals or companies that are exploring crypto, want to earn yield or profit, but don’t want to expose themselves to the risk of a highly volatile market.
  • Traders or investors who want to earn money while trading and want to earn additional returns on their collateral.


flexUSD is currently paying between 10-20% interest a year*, compared to the typical 0.01% interest you see in an average bank savings account.


*These are the current APR figures that flexUSD is experiencing at the time of writing in November, 2021. The APR is variable and changes every 8 hours.


How and why flexUSD was created


Repo and flexUSD

To better understand how this works, let’s briefly learn what Repo is and why the Repo market is so valuable to CoinFLEX.


Traditional Repo markets trade about $2-4 trillion dollars a day. Never heard of it? We don’t blame you. Large financial institutions like banks don’t allow normal people to participate and earn yield in these markets.


CoinFLEX is the first exchange to create a Repo (repurchasing) market, which is a short-term borrow and lending market facilitated by CoinFLEX.


CoinFLEX distributes 90% of the interest earned from these loans.


CoinFLEX created the first Repo market that retail can access, in both traditional finance and crypto. You can participate in this market every hour, on the hour (i.e. 11:00, 12:00, 13:00 etc.) CoinFLEX understands providing access to high yield passive products benefits everyone:

  • Lenders earn money on their yield.
  • Borrowers are able to borrow on their crypto, fully collateralized, without going through the lengthy process of applying via a bank.


What does a CoinFLEX Repo trade look like?

The Buy Repo trade automatically buys spot and sells perp (perpetual futures).

The Sell Repo trade automatically sells spot and buys perp.


A good way to remember it is;

If you buy Repo you’re buying spot.

If you sell Repo you’re selling spot.


In a Buy Repo trade, users are lending their USD and get paid by borrowers.


Why flexUSD was created

In the early days of CoinFLEX Repo trading, it was typical for traders to manually arbitrage between the different Repo pairs. However, this is difficult so we automated the process, leading to the creation of flexUSD.

flexUSD tokenized the Buy Repo trade on CoinFLEX (i.e “Buy Spot, Sell Perp” basis trading) to act like a “smart trader” to look for the best yield opportunities from every repo orderbook.

flexUSD holders are providing liquidity to the Repo markets.


Why flexUSD interest is never negative


flexUSD yield is never negative because it captures the basis difference between perps and spot markets regardless of market direction. It is only when the funding rate in the perps market is 0% when flexUSD does not earn yield.

APRs may be lower in down-trending markets due to the decreased demand for perps, thus decreasing the funding rate.


Can I earn passive income on cryptocurrencies other than USD(C)?

Yes! You earn a yield on other crypto assets in the same way you can earn yield while holding flexUSD.

If you are a holder and don’t want to trade, you can earn passive income from your other crypto (eg. flexBTC) in the same way you can do with US dollars (via USDC).

It works for all kinds of FLEX wrapped assets, from flexBTC, flexETH, flexFLEX to any coins that CoinFLEX has repo markets for.

You can ‘mint’ flexBTC for example and earn extra return in addition to the profit you would make from your Bitcoin appreciating in price.

It’s very similar to staking, except with staking it’s locked on an exchange, liquidity pool, or wallet. At CoinFLEX, you have the ability to move your crypto around and even trade with it while earning yield.


How do you get these flexAssets?

You can create or redeem your assets 1:1 for flexAssets on


Is there a fee to redeem flexUSD?

flexUSD is freely redeemable three times per day. If you would like to instantly redeem flexUSD, you can do so for a small fee, which is the interest of the previous two funding windows. This information displayed in the GUI is based on the current interest rates.


So where’s the second source of yield?

flexUSD can be taken off platform and deployed on DeFi lending platforms allowing you to earn further interest from yield farming.


What rate of returns/yield can I expect?

To get an understanding of what returns you can expect, take a look at the recent history on our transparency page. During times of high market volatility, leverage trading widens the price difference between spot and perp prices. Furthermore, there’s a greater demand and utilization of USD, which results in higher flexUSD APRs.

To avoid market volatility and earn higher APRs, periods of high market volatility are often a popular time to mint flexUSD.


What blockchains do flexUSD/assets exist on?

flexUSD is an ERC20 token and also on the BCH network via SLP (simple ledger protocol) & SmartBCH (SEP20). We will soon be adding flexUSD across all other chains as we want the tokens to be chain agnostic e.g. TRC20, EOS, Polkadot and others.


What are the smart contracts?

Ethereum (ERC20):

Bitcoin Cash (SLP):

SmartBCH (Sep20):


How do I mint flexUSD? Is it easy?

Yes! It’s extremely easy, just enter the flexUSD page on and follow the following steps.

Step 1: Select “Mint”
Step 2: Select the asset you want to mint
Step 3: Enter an amount
Step 4: Click “Confirm” and you will receive a confirmation message at the top of the screen.




When can I redeem the flexAsset and how do I do that?

You can redeem your flexAsset at any time for the native asset but it will be processed and credited at the next auction cycle. Our repo auctions are at 12 noon UTC, 8pm UTC and 4am UTC.

Step 1: Select “Redeem”
Step 2: Select the coin you want to redeem
Step 3: Enter the amount
Step 4: Click the “Confirm” button and you will receive a confirmation message at the top of the screen.



How to borrow the USD?

Step 1: Select “Borrow”
Step 2: Input the amount that you want to borrow
Step 3: Select the collateral coin, it will automatically calculate the amount
Step 4: Click the “Borrow” button, and you will be required to create a Borrow account. Continue to the next step.



Step 5: Click “Confirm Borrow” to continue.




Step 6: Review your History
Go to Borrow & Repay History under flexAssets History in the dashboard of “Wallet & Order”.




1. Borrow coin: USD only;
2. Cannot be less than the minimum amount of 10 USD, and cannot exceed the max borrow, which is calculated by the formula below.




3. Collateral coin: only BTC, ETH, FLEX, BCH. CELR;
4. When borrowing, if don’t have a Borrow account for the coin( eg. ETH or BTC), the system will automatically create a corresponding borrow account after the user agrees to open it;
5. Account type: Borrow

6.Access permission: Same as normal sub account, except that the type is different;
7. LTV: loan to value. the larger the LTV, the higher the risk, the highest is 0.98.



How to repay and get back my collateral?

Step 1: Select “Repay”
Step 2: Input the collateral amount that you want to receive and select the corresponding coin
Step 3: It will show the amount automatically that you need to repay
Step 4: Click the “Repay” button and view the details by clicking the down arrow.




If you have trading experience, you can also directly buy repo or close the position and complete the repayment.

Where can l view the history record?

You can view your records in the Asset History page by clicking the “View History” or the “flexAssets” under the “Wallet & Order”.