structure

agent.py
  ┌─────────────────────────────────────┐
  │ EDITABLE SECTION                    │  ← agent rewrites this
  │   get_signals(data)                 │
  │   get_position_sizes(signals, data) │
  │   get_regime(data)                  │
  └─────────────────────────────────────┘
  ══ FIXED ADAPTER BOUNDARY ════════════════
  ┌─────────────────────────────────────┐
  │ FIXED SECTION                       │  ← never touched
  │   UNIVERSE_SIZE = 300               │
  │   DEV_END = "2016-12-31"            │
  │   HOLDBACK_START = "2017-01-01"     │
  │   HOLDBACK_END = "2018-12-31"       │
  │   WF_START = "2019-01-01"           │
  │   WF_END = "2021-12-31"             │
  │   HOLDOUT_START = "2022-01-01"      │
  │   load_data()                       │
  │   simulate()                        │
  │   compute_metrics()                 │
  │   walk_forward()                    │
  │   CLI entry point                   │
  └─────────────────────────────────────┘

program.md          ← YOU edit this
results.csv         ← auto-generated experiment log
last_result.json    ← auto-generated, last backtest output
.agent/best_dev_agent.py      ← best DEV score snapshot
.agent/best_holdback_agent.py ← best holdback-validated snapshot

quick start

Point your agent at the repo and prompt:

Read program.md and let's start a new experiment.

the only file you edit

program.md — change the research directive, the hypothesis space, or the target metrics. The agent reads this to decide what to try.

score formula

score = sharpe
      - max(0, (turnover - 0.3) * 0.5)
      - max(0, (|max_drawdown| - 0.20) * 2)

data split

Period	Dates	Purpose
Development	2010–2016	Iterate freely
IS Holdback	2017–2018	One-shot gate per hypothesis
Walk-forward	2019–2021	One-shot validation per hypothesis
Holdout	2022–present	Locked until final run

stopping criteria

Condition	Meaning
Walk-forward passes	Target achieved
200 iterations	Time limit

assumptions

• Transaction cost: 10bps per rebalance
• Universe: top 300 stocks by 30-day average dollar volume (selected on IS data only)
• Execution: 1-day lag on all signals

customizing

• Different asset class: swap the tickers in SP500_TICKERS for ETFs, futures, crypto
• Different score formula: edit compute_metrics() in the fixed section AND update program.md
• Different split: change the date constants in the fixed section — this invalidates cross-experiment comparisons
• Larger universe: change UNIVERSE_SIZE in the fixed section — this invalidates cross-experiment comparisons

what's next

1. Survivorship bias: delisted stocks weren't included in the MVP
2. More realistic costs: 10bps/trade may be optimistic for this universe
3. Sharpe discounting for iteration: The score formula does not penalize for the number of iterations run.
4. Walk-forward leakage: Since the agent can see walk-forward results, some overfitting may occur despite being prompted to generate novel hypotheses. I plan to address this with a dedicated check agent to verify hypothesis novelty.

Note: The expanding window is only structurally meaningful if get_signals() estimates parameters from data. With hardcoded parameters, the three folds reduce to a single OOS backtest split into thirds.