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

# Rate Order Book

***

Exponent’s **Rate Order Book** is a fully onchain limit order book for trading fixed-rate and yield exposure through an **Implied APY**.

Rather than quoting an asset price like a traditional exchange, Exponent quotes interest-rate assets directly in annualized yield terms. This allows users to place bids and asks around the rate they want to lock, pay, or receive until maturity.

The Rate Order Book is designed for participants who want **precise execution**, **explicit limit pricing**, and **deeper control over entry and exit levels** when trading PT and YT.

## Why a Rate Order Book?

Interest-rate assets are not best understood through spot prices alone.

On Exponent, PT and YT represent two sides of a yield market with a fixed maturity. What traders usually care about is not just “what is the token worth right now?”, but rather:

* what **fixed rate** can be locked today
* what **forward yield** the market is implying
* whether that rate is attractive relative to expected realized yield

By quoting orders in **Implied APY**, the Rate Order Book makes yield markets easier to reason about for active participants.

## How It Works

The Exponent Rate Order Book matches participants who want to buy or sell yield exposure at a specific rate.

Users can post limit orders for:

* **YT directly**, for pure yield trading
* **PT virtually**, using the same underlying liquidity

This is possible because PT and YT are mathematically linked through the underlying yield-stripping market. Internally, the order book shares liquidity across both exposures, allowing users to access fixed-rate and variable-yield trading through one unified venue.

### What gets traded?

There are two main exposures on Exponent:

* **PT (Principal Token)** – the fixed-rate side of the market. PT trades at a discount and converges to par at maturity.
* **YT (Yield Token)** – the variable-yield side of the market. YT gives exposure to the yield generated by the underlying asset until maturity.

The Rate Order Book lets users trade either side, while pricing everything through the market’s **Implied APY**.

## PT and YT Share Liquidity

One of the core design features of the Exponent Rate Order Book is that **PT and YT do not need separate liquidity silos**.

All orders are internally represented around YT-side liquidity. When a user wants to trade PT, Exponent automatically handles the required strip or merge logic under the hood through Exponent Core's [yield stripping](/user-documentation/yield-stripping-swap).

This means:

* **buying PT** can route through YT-side liquidity
* **selling PT** can also route through the same book
* liquidity is more unified and capital efficient than having isolated PT and YT books

For users, the experience remains simple: choose the side of the market to trade and the rate you want.

## Limit Orders and Market Orders

The Rate Order Book supports both passive and active execution styles:

<Tabs>
  <Tab title="Limit Orders">
    Limit orders let users specify the Implied APY they are willing to trade at.

    This is useful when:

    * targeting a specific fixed rate
    * waiting for a better entry on YT
    * providing passive liquidity to the market
    * managing execution on larger positions

    Orders rest onchain until they are filled, expire, or are removed.
  </Tab>

  <Tab title="Market Orders">
    Market orders execute immediately against available liquidity on the book.

    This is useful when:

    * entering or exiting quickly matters more than price precision
    * the market already offers a rate that looks attractive
    * a user wants immediate exposure without waiting for a counterparty
  </Tab>
</Tabs>

## Why Use the Order Book Instead of the CLMM?

The Rate Order Book and the Rate CLMM serve different trading needs.

|                     | Rate Order Book                           | Rate CLMM                                    |
| ------------------- | ----------------------------------------- | -------------------------------------------- |
| Execution style     | Limit-based, discrete price levels        | Continuous liquidity across a rate range     |
| Best for            | Precise entries and exits                 | Fast routing and passive two-sided liquidity |
| User type           | Active traders, larger orders, rate views | Traders and LPs seeking continuous liquidity |
| Pricing control     | Exact rate targeting                      | Execution within available pool range        |
| Liquidity provision | Passive orders resting on the book        | Active LP positions in chosen APY ranges     |

In practice, the order book is often more attractive for users who want **clean limit execution** around a target rate, while the CLMM is better for **continuous market making and tighter always-on liquidity**.

## Who Is It For?

The Rate Order Book is especially useful for:

* **fixed-rate buyers** who want to lock a minimum target return
* **yield traders** who want to buy or sell YT at a precise implied yield
* **larger participants** who want more control over slippage and execution
* **market makers** who prefer quoting passively at specific levels rather than managing a CLMM range

## Before and After Maturity

Like all Exponent yield markets, the Rate Order Book operates around a **fixed maturity date**:

<Tabs>
  <Tab title="Before maturity">
    * PT and YT can trade freely
    * orders are quoted in Implied APY
    * rates move based on supply and demand
  </Tab>

  <Tab title="At maturity">
    * the trading window for that market ends
    * PT converges to par
    * YT no longer has future yield remaining
    * open trading activity on that maturity stops
  </Tab>
</Tabs>

Because of this, order book trading is most relevant during the life of the market, when future yield is still uncertain and rates are still being discovered.

## Risks and Considerations

Using the Rate Order Book involves a few important considerations:

* **Execution risk** – limit orders may not fill if the market never reaches your target rate
* **Partial fills** – depending on liquidity, an order may fill only partially
* **Market risk** – Implied APY can move quickly as participants reprice future yield expectations
* **Liquidity risk** – some maturities may have thinner depth than others, especially for larger trades
* **Smart contract risk** – applies to the order book, core protocol logic, and underlying yield source

For PT positions, holding until maturity removes most interim mark-to-market uncertainty. For YT positions, outcomes remain dependent on realized yield and time remaining.

## FAQ and Common Issues

<AccordionGroup>
  <Accordion title="What does the order book quote in?">
    Orders are quoted in **Implied APY**, not in a simple token spot price. This makes interest-rate trades easier to reason about in terms of the yield being locked or paid.
  </Accordion>

  <Accordion title="Can I trade both PT and YT on the same order book?">
    Yes. The Exponent Rate Order Book supports both PT and YT exposure, with PT routing handled through the same underlying liquidity.
  </Accordion>

  <Accordion title="Why didn’t my limit order fill?">
    Your order only fills if the market reaches your quoted rate and another participant matches it. If the market trades away from your level, your order can remain open until expiry or manual removal.
  </Accordion>

  <Accordion title="Is the order book better than the CLMM?">
    They serve different purposes. The order book is better for precise pricing and active execution. The CLMM is better for continuous liquidity and concentrated market making.
  </Accordion>

  <Accordion title="What happens to my order at maturity?">
    Trading for that maturity effectively ends. Unfilled orders stop being useful, and PT/YT settle according to the market’s maturity mechanics.
  </Accordion>
</AccordionGroup>