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

# The opening window

> A temporary buy surcharge that decays with chain time.

The deployed mainnet policy applies an additional surcharge to buys during every new launch's opening period. This covers FX-pair, single-currency, and dedicated official-FX launches. Each launch starts its clock after its canonical pool or pools are seeded.

An FX-pair launch shares **one clock across both token pools**. Activation cannot restart, and the surcharge remains zero after expiry.

## The current configured curve

The deployed R6 policy starts at **99%**, uses a nominal **500-millisecond half-life**, and expires after **five seconds**. These values are fixed in the [release policy contract](/developers/contracts#revenue-and-policy).

EVM timestamps resolve to whole seconds. The half-life describes the curve's parameter, rather than a timer that executes twice every second.

| Elapsed chain time | Surcharge rate |
| ------------------ | -------------: |
| 0 seconds          |         99.00% |
| 1 second           |         24.67% |
| 2 seconds          |          6.09% |
| 3 seconds          |          1.45% |
| 4 seconds          |          0.29% |
| 5 seconds onward   |             0% |

These rates apply to the quote remainder **after ordinary hook fees**. Always check the actual deployment's opening policy.

## Calculation order

```text theme={null}
normalFee = floor(grossQuote × normalRateBps / 10,000)
remainder = grossQuote − normalFee
openingFee = floor(remainder × openingRateBps / 10,000)
quote reaching the native pool = remainder − openingFee
```

For a 100-USDC FX-pair buy at elapsed time zero:

| Step                                    |    USDC |
| --------------------------------------- | ------: |
| Gross quote input                       | 100.000 |
| Ordinary 0.10% protocol hook fee        |   0.100 |
| Remainder                               |  99.900 |
| Opening surcharge: 99% of the remainder |  98.901 |
| Quote reaching the native pool          |   0.999 |

The native LP fee then applies on its own fee base. This example shows why the opening surcharge materially changes an immediate launch-time purchase.

## Which trades pay it

Purchases through the canonical hooked pools pay the applicable surcharge, including purchases submitted by a different router or directly through PoolManager.

Sells pay normal fees only. A separate secondary pool may have different rules.

## Where it goes

The entire additional surcharge is protocol-owned revenue. It is collected in the local quote currency and follows the same [90% buyback / 10% operations accounting](/economics/fx-token) after USDC realization.

It does not go to the creator or token holders. It does not trigger a currency conversion or \$FX purchase synchronously inside the trader's swap.

## What it changes

The surcharge makes immediate extraction at the opening price expensive. It does not identify bots, eliminate sniping, or guarantee a protected price. Traders can wait for the window to expire.

Its activation time is a chain timestamp. A browser countdown is a display of that policy, not the authority that sets the fee.