ZipLime/congress-trading

🏛️ US Congress Trading Disclosures (PIT)

Securities transactions disclosed by members of the US Congress under the STOCK Act, point-in-time by disclosure date.

Part of the ziplime Point-in-Time (PIT) data layer — append-only datasets with an explicit split between when a fact happened (event_date) and when it became known (knowledge_date). A simulation at time T can only ever observe rows with knowledge_date <= T, so restatements, publication lag and hindsight can't leak into a backtest. The identical code path runs live with T = now.

• Data class: Alternative data — political trading disclosures
• Entity domain: us_equities — The traded US-listed security (ticker); the filer is carried as a value column.
• Origin: US House Clerk & Senate eFD periodic transaction reports (STOCK Act)
• License: US Government work — public domain
• Update cadence: daily, sweeping newly published periodic transaction reports (0 6 * * *)
• Format: ziplime Delta Lake bundle (data_type: PIT_DATA)

Why point-in-time?

Backtests on non-price data are systematically optimistic when the data layer has no notion of when a fact became known. Three failure modes this dataset is built to avoid:

1. Restatements — a value reported one quarter and revised the next. Storing only the final value lets a backtest "know" the revision months early.
2. Publication lag — fundamentals keyed by fiscal-period-end, joined to prices at period end rather than the (weeks-later) filing date.
3. Hindsight in derived signals — a recent model scoring old text has already seen how the story ended.

All three are the same bug, and it is fixed in the data layer, not in strategy code.

Estimated knowledge dates: rows where the source gives no publication time are modelled with the stock_act_statutory_45d lag and marked knowledge_estimated = true. Filter or discount them for a stricter run.

Schema

System columns (every PIT dataset)

Column	Type	Semantics
entity_id	Utf8	Stable entity identifier (resolved via the entity_map PIT dataset)
event_date	Timestamp(UTC, µs)	The moment the fact refers to
knowledge_date	Timestamp(UTC, µs)	The moment it became publicly known — the only column the as-of filter uses
knowledge_estimated	Boolean	true if knowledge_date was reconstructed by a lag model rather than taken from the source
ingested_at	Timestamp(UTC, µs)	When our pipeline wrote the row (audit only; never used in as-of)

Value columns (this dataset)

Column	Type	Description
representative	Utf8	Name of the filing member of Congress
chamber	Utf8	house or senate
transaction_type	Utf8	purchase / sale / exchange
asset_ticker	Utf8	Traded ticker (mirrors entity_id)
amount_low	Float64	Disclosed USD range, lower bound
amount_high	Float64	Disclosed USD range, upper bound
disclosure_lag_days	Int64	Days between trade and public disclosure

The logical key of a fact is (entity_id, event_date). A revision is a new row with the same key and a later knowledge_date. Written rows are immutable; history is never rewritten.

As-of access

Inside a ziplime strategy there is no T parameter — the knowledge moment always equals the simulation clock (live: wall clock):

async def initialize(context):
    context.ds = await context.pit("congress-trading")

async def handle_data(context, data):
    # only rows with knowledge_date <= current simulation time are visible
    latest = await context.ds.latest(
        assets=[context.asset], fields=['representative', 'chamber']
    )
    history = await context.ds.as_of(
        assets=[context.asset], fields=['representative'],
        event_range=("2022-01-01", None),
    )

Reading it outside ziplime (plain Polars + delta-rs)

import polars as pl

T = "2025-06-01T00:00:00Z"          # "what was known at T"
lf = pl.scan_delta("hf://datasets/ZipLime/congress-trading/data/data_bundle/yahoo_finance_daily_data/1784755946/data.delta")
as_of = (
    lf.filter(pl.col("knowledge_date") <= T)
      .sort("knowledge_date")
      .group_by(["entity_id", "event_date"], maintain_order=True)
      .last()
)
print(as_of.collect())

Delta time-travel (AS OF <version>) pins the table for reproducibility; the knowledge_date <= T filter is what enforces point-in-time. They compose: a backtest records (dataset, delta_version) and replays read the table at that version and apply the filter.

Updates

recipe.py implements the collection contract fetch(since: datetime) -> pl.DataFrame in the PIT schema above; ingest.py dedups and appends to the Delta bundle (never rewrites). The scheduled job in .github/workflows/update.yml runs it daily, sweeping newly published periodic transaction reports.

# recipe.py (contract)
async def fetch(since: datetime) -> "pl.DataFrame": ...

Knowledge-date convention

knowledge_date = the disclosure filing timestamp. The STOCK Act allows members to disclose up to 45 days after a trade, so event_date (trade date) can lead knowledge_date by weeks — exactly the publication-lag trap PIT exists to close. Filings that carry only a date (no time) are rounded up to end-of-day ET; filings with no timestamp at all fall back to event_date + 45d and are flagged knowledge_estimated = true.

What's in this repo

README.md                     # this card
manifest.json                 # PIT dataset manifest (schema, source, schedule)
recipe.py                     # fetch(since) -> PIT rows
ingest.py                     # dedup + append-only Delta writer
.github/workflows/update.yml  # scheduled ingestion
data/                         # ziplime Delta bundle + registry manifest
  bundle_registry/yahoo_finance_daily_data_1784755946.json
  data_bundle/yahoo_finance_daily_data/1784755946/data.delta/

The data/ bundle is a ready-to-load ziplime Delta Lake market-data bundle (five US equity tickers, daily bars) that seeds the pipeline and lets you exercise the loader end-to-end today. Point pl.scan_delta (above) at it, or register it with ziplime's FileSystemBundleRegistry.

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_{Generated for the ziplime PIT data-layer prototype. Manifest and schema follow the ziplime PIT spec; source.* fields declare origin and license per the dataset manifest.}