Anti-Snipe Mechanics & Decaying Taxes
In the first three seconds of a public token launch, automated MEV bots can drain the lowest bonding curve prices before human buyers load the page. Decaying anti-snipe taxes neutralize this bot advantage by taxing opening buys at up to 99%.
The short answer
A decaying anti-snipe tax is a dynamic fee applied to buys during the earliest seconds of a token’s existence.
On platforms like Pons (Robinhood Chain), opening buys start with a 99% tax (9,900 bps) that decays linearly to 0% over a 3-second window. Any predatory bot sniping the pool immediately loses 99% of its capital to the protocol. To permit legitimate launch participants to seed the market, the contract supports an explicit exemption list (snipeTaxExemptions) for the creator and coordinated block-0 bundles.
The Opening-Block Sniper Problem
When a liquidity pool or bonding curve is created, the price per token is at its absolute theoretical minimum.
Predatory snipers exploit this through:
- Pending-Mempool Sniffing: Bots monitor validators or pending transactions to detect the
createTokenor pair creation transaction. - Gas Bribes / Priority Fees: Bots submit buy orders with maximum priority tips, ensuring their buy lands in the exact same block immediately behind the pool creation.
- Dumping on Retail: Seconds later, as human community members attempt to enter, the bot dumps its cheap tokens, extracting all liquidity and killing the token’s momentum.
How Pons Implements Decaying Taxes
On Robinhood Chain, the Pons factory contract natively integrates a time-decaying formula:
// Pons protocol constants
PONS_SNIPE_TAX_START_BPS = 9900; // 99.00%
PONS_SNIPE_TAX_SECONDS = 3; // 3 seconds decay window
When a buy arrives at timestamp t:
- The contract calculates elapsed time:
elapsed = t - launchTimestamp. - If
elapsed < 3 seconds, the effective tax is:currentTax = 9900 * (3 - elapsed) / 3
- If
elapsed >= 3 seconds, the tax drops permanently to 0% (or the configured creator tax).
Exemption Whitelists & Block-0 Bundles
If the opening tax is 99%, how does the dev or coordinated team buy without losing their funds?
The contract accepts an array of exempted addresses:
snipeTaxExemptions: address[]
- Creator Exemption: The deploying wallet is automatically added to the exemption list.
- Block-0 Sniper Vault: In Trenchables, pre-configured sniper wallets can be passed into the exemption list within the launch transaction. Their buys execute at block zero with 0% snipe tax, while external sniper bots hitting the same block pay the full 99%.
Comparing Anti-Snipe Strategies
| Method | Strengths | Weaknesses |
|---|---|---|
| Decaying Tax (Pons) | Burns bot capital; fully on-chain | Requires honest duration disclosure to users |
| Jito Atomic Bundles | Zero mempool exposure; private landing | Solana-specific; tip competition |
| Max Tx Limits | Prevents single-wallet supply cornering | Bots easily bypass using multi-wallet sybils |
| Block/Slot Delays | Simple to implement in Solidity | Creates pent-up MEV wars on the unlock block |
Operator Checklist for Anti-Snipe Launches
- Verify Exemption Addresses: Ensure every wallet in your block-0 bundle is explicitly included in
snipeTaxExemptions. - Inform Community of the 3-Second Window: Tell manual traders to wait 5 seconds after launch to ensure the decay curve has completely settled to 0%.
- Do Not Rely on Tx Limits Alone: Sybil bot clusters use 50+ wallets; pair limits with fee decay or atomic bundling.
- Monitor Initial Liquidity Depth: Confirm that taxes collected from failed bot attempts are properly credited according to the factory logic.
Primary and official sources
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