The yield market
Spield's time-decay AMM for trading PT and YT, with a live implied-APY headline and two human-friendly flows — Earn Fixed and Long Yield.
The market is where PT and YT change hands. It's a purpose-built time-decay AMM — an automated market maker whose pricing understands that PT marches to par and YT decays to zero as maturity approaches. You never see raw curve math; you see two simple flows and a headline rate.
The headline: implied APY
The market's main number is the implied APY — the annualized return you'd lock in by buying PT right now and holding to maturity. It's derived live from the PT price and the time remaining, and it updates as people trade.
Implied vs realized
The implied APY is the market's current expectation of yield. The realized APY is what actually accrues. A gap between them is the opportunity: if you think realized yield will beat the implied number, that's a reason to go long yield (buy YT); if you think it'll fall, lock the fixed rate (buy PT).
Two human flows
The market presents trading as two clear actions rather than as buy/sell of abstract tokens.
Earn Fixed = buy PT. You pay USDC, receive PT at a discount, and hold it to maturity for a guaranteed return at today's implied APY.
- Best for: savers who want certainty and like the current fixed rate.
- Result: a known return, locked in.
- To exit before maturity: sell the PT back at the then-current price.
Long Yield = get leveraged YT exposure. Behind one click, the protocol mints PT + YT from your USDC and sells the PT back into the market, leaving you holding YT for a small net cost. A little capital buys exposure to the yield of a much larger position.
- Best for: traders who think realized yield will exceed the implied APY.
- Result: amplified upside if yields run hot; YT can decay to zero if they don't.
- This is the higher-risk flow — see risks.
Why a time-decay curve?
A normal AMM (like a constant-product DEX) has no concept of time. It would force liquidity providers to fight against PT's natural rise to par — guaranteeing them losses. Spield's curve is different: it expects PT to drift to par and YT to zero, and prices accordingly.
The practical payoff:
- Traders get prices that reflect the real, time-aware value of PT and YT.
- Liquidity providers who hold to maturity bear near-zero impermanent loss for PT's predictable march to par (see Liquidity).
Slippage and quotes
Every trade shows a live quote before you confirm, and you can set a slippage tolerance (e.g. 0.5% / 1% / 2%) so a trade only executes within the price you accept. If a trade would exceed available liquidity, the app tells you instead of failing silently.
Trading stops at maturity
Once a market reaches maturity, trading halts — there's nothing left to price, since PT is simply redeemable 1:1 for USDC. Liquidity providers can still withdraw at any time, including after maturity.
Related
- Walkthroughs: Earn a fixed yield · Go long on yield
- Earn fees from this market: Liquidity
PT & YT tokens
Spield's Principal Tokens and Yield Tokens are real, composable Stellar assets — mint them, hold them, claim yield, redeem, or trade them.
Liquidity provision
Provide PT + USDC to Spield's market to earn swap fees, with near-zero impermanent loss if you hold to maturity thanks to the time-decay design.