Price Oracles

OUSD is designed to stay pegged at 1 USD and be 1:1 backed with its underlying stablecoins. This is trickier than it sounds because these underlying stablecoins are constantly deviating from their own desired 1 USD pegs. While the majority of daily fluctuations are minor, there have been major swings in price that have occurred in the past and are likely to occur again in the future.

The rebasing function treats 1 stablecoin as 1 OUSD for simplicity and to protect OUSD balances from being affected by the daily fluctuations in the price of the underlying stablecoins. Since the rebase function only counts coins, OUSD balances should only increase.

In order to mint and redeem the appropriate number of OUSD on entry and exit, the smart contracts need to accurately price the USDT, USDC, and DAI that is entering and exiting the system. As a decentralized protocol, OUSD must rely on non-centralized sources for these prices.

In order to prevent malicious attacks and to encourage long-term investors over short-term speculators, the OUSD contract compares price feeds from multiple sources and will use whichever exchange rate benefits the entire pool over the individual. This mechanism protects the pool's funds from arbitrageurs and prevents any individual from being able to take advantage of any temporary inefficiencies caused by mispriced oracles to deplete the shared pool of assets.

This protects the funds in the pool while rewarding long-term holders. Since the safest price depends on the direction of the trade, the Origin oracle exposes both a priceUSDMint() and a priceUSDRedeem().

Here is the initial set of oracles that are being used by OUSD:

The following oracles have been implemented, but are not currently being used due to gas costs:

It is possible that additional oracles will be added to the protocol over time. Support may also be removed if any of these oracles become unreliable.