> ## 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.

# Buy PT (Exact Out)

> Low-level instruction to buy an exact amount of PT tokens

# createTradePtExactOutInstruction

Buys an exact amount of PT tokens by specifying the desired output amount. This instruction uses `createTradePtExactOutInstruction` with `swapDirection: { buyPt: {} }` to purchase a precise quantity of PT from the CLMM market, spending SY tokens as input. The caller specifies the exact PT amount to receive, and an optional maximum SY input constraint can be set for slippage protection.

## Usage

```typescript theme={null}
import { createTradePtExactOutInstruction } from "@exponent-labs/exponent-sdk/client/clmm";
import { PublicKey } from "@solana/web3.js";

const ix = createTradePtExactOutInstruction({
  trader: traderKeypair.publicKey,
  market: new PublicKey("market..."),
  ticks: new PublicKey("ticks..."),
  tokenSyTrader: new PublicKey("tokenSyTrader..."),
  tokenPtTrader: new PublicKey("tokenPtTrader..."),
  tokenSyEscrow: new PublicKey("tokenSyEscrow..."),
  tokenPtEscrow: new PublicKey("tokenPtEscrow..."),
  addressLookupTable: new PublicKey("lookupTable..."),
  tokenProgram: new PublicKey("TokenkegQfeZyiNwAJbNbGKPFXCWuBvf9Ss623VQ5DA"),
  syProgram: new PublicKey("syProgram..."),
  tokenFeeTreasurySy: new PublicKey("tokenFeeTreasurySy..."),
  tokenFeeTreasuryPt: new PublicKey("tokenFeeTreasuryPt..."),
  eventAuthority: new PublicKey("eventAuthority..."),
  program: new PublicKey("program..."),
  amountOut: 1_000_000n,
  swapDirection: { buyPt: {} },
  amountInConstraint: 1_100_000n,
  priceSpotLimit: 0.95,
});
```

## Accounts

| Name                 | Type        | Signer | Writable | Description                   |
| -------------------- | ----------- | ------ | -------- | ----------------------------- |
| `trader`             | `PublicKey` | Yes    | Yes      | Wallet executing the trade    |
| `market`             | `PublicKey` | No     | Yes      | The CLMM market account       |
| `ticks`              | `PublicKey` | No     | Yes      | The market tick array account |
| `tokenSyTrader`      | `PublicKey` | No     | Yes      | Trader's SY token account     |
| `tokenPtTrader`      | `PublicKey` | No     | Yes      | Trader's PT token account     |
| `tokenSyEscrow`      | `PublicKey` | No     | Yes      | Market SY escrow account      |
| `tokenPtEscrow`      | `PublicKey` | No     | Yes      | Market PT escrow account      |
| `addressLookupTable` | `PublicKey` | No     | No       | Market address lookup table   |
| `tokenProgram`       | `PublicKey` | No     | No       | SPL Token program             |
| `syProgram`          | `PublicKey` | No     | No       | SY program                    |
| `tokenFeeTreasurySy` | `PublicKey` | No     | Yes      | SY fee treasury account       |
| `tokenFeeTreasuryPt` | `PublicKey` | No     | Yes      | PT fee treasury account       |
| `eventAuthority`     | `PublicKey` | No     | No       | Event authority PDA           |
| `program`            | `PublicKey` | No     | No       | CLMM program ID               |

## Args

| Name               | Type             | Description                                              |
| ------------------ | ---------------- | -------------------------------------------------------- |
| amountOut          | `u64`            | The exact amount of PT tokens to receive                 |
| swapDirection      | `SwapDirection`  | Set to `{ buyPt: {} }` to buy PT                         |
| amountInConstraint | `u64` (optional) | The maximum amount of SY to spend as slippage protection |
| priceSpotLimit     | `f64` (optional) | The price limit for the trade                            |

## Returns

`TransactionInstruction` — a transaction instruction ready to be added to a transaction.