Near-expiry conviction trading on Polymarket. The skill scans markets in their final minutes, filters for strongly-skewed splits (60/40+), and places bounded...
---
name: polymarket-mert-sniper
description: Near-expiry conviction trading on Polymarket. The skill scans markets in their final minutes, filters for strongly-skewed splits (60/40+), and places bounded trades against the under-priced side. Defaults โ $10 max per trade, 5 trades/run, dry-run unless `--live`.
metadata:
author: Simmer (@simmer_markets)
version: "1.3.2"
displayName: Mert Sniper
difficulty: advanced
attribution: Strategy inspired by @mert โ https://x.com/mert/status/2020216613279060433
---
# Mert Sniper
Near-expiry conviction trading on Polymarket. The skill scans markets in their final minutes of pricing, filters for strongly-skewed splits, and places bounded trades against the under-priced side.
> ๐จ **Framework, not a production trading system.** Read [DISCLAIMER.md](./DISCLAIMER.md) before connecting to a wallet with real funds. Dry-run is the default; `--live` is required for any real-USDC trade. Defaults: $10 max per trade, 60/40 split minimum, 2-minute expiry window, 5 trades per scan cycle โ adjust deliberately before scaling.
> **This is a template.** The default logic (expiry + split filter) is a starting point โ remix it with your own filters, timing rules, or market selection criteria. The skill handles all the plumbing (market discovery, trade execution, safeguards). Your agent provides the alpha.
> Strategy attribution: [@mert](https://x.com/mert/status/2020216613279060433) โ see source thread for the original methodology (topic filter, near-expiry timing, strong-split entry).
## When to Use This Skill
Use this skill when the user wants to:
- Trade markets that are about to resolve (last-minute conviction bets)
- Filter by topic (e.g. only SOL/crypto markets)
- Cap bet size (e.g. never more than $10)
- Only trade when odds are strongly skewed (e.g. 60/40 or better)
- Run an automated expiry-sniping strategy
## Setup Flow
1. **Install the Simmer SDK**
```bash
pip install simmer-sdk
```
2. **Ask for Simmer API key**
- Get it from simmer.markets/dashboard -> SDK tab
- Store in environment as `SIMMER_API_KEY`
3. **Ask for wallet private key** (required for live trading)
- This is the private key for their Polymarket wallet (the wallet that holds USDC)
- Store in environment as `WALLET_PRIVATE_KEY`
- The SDK uses this to sign orders client-side automatically โ no manual signing needed
4. **Ask about settings** (or confirm defaults)
- Market filter: Which markets to scan (default: all)
- Max bet: Maximum per trade (default $10)
- Expiry window: How close to resolution (default 2 minutes)
- Min split: Minimum odds skew (default 60/40)
5. **Save settings to config.json or environment variables**
## Configuration
| Setting | Environment Variable | Default | Description |
|---------|---------------------|---------|-------------|
| Market filter | `SIMMER_MERT_FILTER` | (all) | Tag or keyword filter (e.g. `solana`, `crypto`) |
| Max bet | `SIMMER_MERT_MAX_BET_USD` | 10.00 | Maximum USD per trade |
| Expiry window | `SIMMER_MERT_EXPIRY_MINUTES` | 2 | Only trade markets resolving within N minutes |
| Min split | `SIMMER_MERT_MIN_SPLIT` | 0.60 | Only trade when YES or NO >= this (e.g. 0.60 = 60/40) |
| Max trades/run | `SIMMER_MERT_MAX_TRADES_PER_RUN` | 5 | Maximum trades per scan cycle |
| Smart sizing % | `SIMMER_MERT_SIZING_PCT` | 0.05 | % of balance per trade |
| Fee buffer | `SIMMER_MERT_FEE_BUFFER` | 0.02 | Extra alpha required above entry fee; only applies when `SIMMER_MERT_MIN_EDGE` is set |
| Declared edge | `SIMMER_MERT_MIN_EDGE` | 0.00 | Your signal's claimed edge above market price (probability units). At 0 (default): fee is logged but gate is advisory only. Set to X to block trades where entry fee > X โ e.g. `0.05` requires your signal to clear at least 5ยข above market after fees |
## Quick Commands
```bash
# Check account balance and positions
python scripts/status.py
# Detailed position list
python scripts/status.py --positions
```
**API Reference:**
- Base URL: `https://api.simmer.markets`
- Auth: `Authorization: Bearer $SIMMER_API_KEY`
- Portfolio: `GET /api/sdk/portfolio`
- Positions: `GET /api/sdk/positions`
## Running the Skill
```bash
# Dry run (default -- shows opportunities, no trades)
python mert_sniper.py
# Execute real trades
python mert_sniper.py --live
# Filter to specific markets
python mert_sniper.py --filter solana
# Custom expiry window (5 minutes)
python mert_sniper.py --expiry 5
# With smart position sizing (uses portfolio balance)
python mert_sniper.py --live --smart-sizing
# Check positions only
python mert_sniper.py --positions
# View config
python mert_sniper.py --config
# Disable safeguards (not recommended)
python mert_sniper.py --no-safeguards
```
## How It Works
Each cycle the script:
1. Fetches active markets from Simmer API (optionally filtered by tag/keyword)
2. Filters to markets resolving within the expiry window (default 2 minutes)
3. Checks the price split -- only trades when one side >= min_split (default 60%)
4. Determines direction: backs the favored side (higher probability)
5. **Fee logging**: prints entry-fee cost per market (`POLY_FEE_RATE_CRYPTO ร p ร (1-p)`, entry only โ redemption is free). If `SIMMER_MERT_MIN_EDGE > 0`, gates out markets where declared edge < entry fee + buffer
6. **Safeguards**: Checks context for flip-flop warnings, slippage, market status
7. **Execution**: Places trade on the favored side, capped at max bet
8. Reports summary of scanned, filtered, and traded markets
## Example Output
```
๐ฏ Mert Sniper - Near-Expiry Conviction Trading
==================================================
[DRY RUN] No trades will be executed. Use --live to enable trading.
Configuration:
Filter: solana
Max bet: $10.00
Expiry window: 2 minutes
Min split: 60/40
Max trades: 5
Smart sizing: Disabled
Safeguards: Enabled
Fetching markets (filter: solana)...
Found 12 active markets
Markets expiring within 2 minutes: 2
SOL highest price on Feb 10?
Resolves in: 1m 34s
Split: YES 72% / NO 28%
Side: YES (72% >= 60%)
[DRY RUN] Would buy $10.00 on YES
Summary:
Markets scanned: 12
Near expiry: 2
Strong split: 1
Trades executed: 0
[DRY RUN MODE - no real trades executed]
```
## Troubleshooting
**"No markets found"**
- Check your filter -- try without a filter first
- Markets may not be available (check simmer.markets)
**"No markets expiring within window"**
- Increase expiry window: `--expiry 10` (10 minutes)
- Or run more frequently (cron every minute)
**"Split too narrow"**
- Lower the min split: `--set min_split=0.55`
- This trades more often but with less conviction
**"Resolves in: 17h" on 15-min markets**
- Polymarket's `endDate` is the event-level end-of-day, not the individual market close time
- For 15-min crypto markets (e.g. "BTC Up or Down - Feb 8, 11PM ET"), the actual close time is in the question text but not in the API
- This is a Polymarket data limitation โ widen the expiry window (`--expiry 1080`) as a workaround, or use the split filter to find conviction opportunities regardless of timing
**"External wallet requires a pre-signed order"**
- `WALLET_PRIVATE_KEY` is not set in the environment
- The SDK signs orders automatically when this env var is present โ no manual signing code needed
- Fix: `export WALLET_PRIVATE_KEY=0x<your-polymarket-wallet-private-key>`
- Do NOT attempt to sign orders manually or modify the skill code โ the SDK handles it
**"Balance shows $0 but I have funds on Polygon"**
- Polymarket V2 (live 2026-04-28) uses **pUSD** (PolyUSD, 1:1 backed by USDC.e). If your wallet holds USDC.e, migrate at [simmer.markets/dashboard](https://simmer.markets/dashboard) with one click (~30s)
- If you bridged native USDC (Circle), swap to USDC.e first, then migrate to pUSD
- Full migration guide: [docs.simmer.markets/v2-migration](https://docs.simmer.markets/v2-migration)
**"API key invalid"**
- Get new key from simmer.markets/dashboard -> SDK tab
don't have the plugin yet? install it then click "run inline in claude" again.