HKUDS/Vibe-Trading · error · ValueError

events is empty

Error message

events is empty

What it means

event_study requires a non-empty events collection; with no events there is nothing to aggregate into AAR/CAAR and statistics would be undefined, so it fails fast with a clear message.

Source

Thrown at agent/src/quantlib/eventstudy.py:358

    Raises:
        ValueError: If the window bounds are inconsistent, ``estimation_gap`` is
            negative, ``model`` is unknown, the market series does not cover the
            frame's index, or no event at all could be measured.
    """
    start, end = event_window
    if start > end:
        raise ValueError(f"event_window start must be <= end, got {event_window}")
    if estimation_gap < 0:
        raise ValueError(f"estimation_gap must be >= 0, got {estimation_gap}")
    if estimation_window < MIN_ESTIMATION_OBSERVATIONS:
        raise ValueError(
            f"estimation_window must be at least {MIN_ESTIMATION_OBSERVATIONS}, "
            f"got {estimation_window}"
        )
    if model not in NORMAL_RETURN_MODELS:
        raise ValueError(f"model must be one of {NORMAL_RETURN_MODELS}, got {model!r}")
    if not events:
        raise ValueError("events is empty")

    index = returns.index
    missing_market = index.difference(market_returns.index)
    if len(missing_market):
        raise ValueError(
            f"market_returns is missing {len(missing_market)} label(s) present in "
            "returns; align them before calling"
        )
    market_aligned = market_returns.reindex(index)

    relative_days = list(range(start, end + 1))
    window_len = len(relative_days)

    outcomes: list[EventOutcome] = []
    dropped: list[tuple[str, object, str]] = []

    for symbol, event_date in events:
        if symbol not in returns.columns:

View on GitHub (pinned to 80ffdda44c)

Solutions

1. Guard before calling: if not events: skip/log.
2. Widen the event date selection or fix the upstream filter that emptied the collection.

Example fix

# before
result = event_study(returns, market, events, (0, 0))
# after
result = event_study(returns, market, events, (0, 0)) if events else None

if not events:
    raise SystemExit("no events to study")

def has_events(events) -> bool:
    return bool(events)

When it happens

Trigger: Passing events=[] or an empty dict/list, usually because an upstream filter (e.g. date range or universe screen) removed all events.

Common situations: Backtesting a period with no qualifying event dates, an events DataFrame filtered to zero rows, or a loop iteration where the last chunk is empty.

Related errors

• brinson_fachler needs at least one sector
• label_end_times is empty
• groups array cannot be empty
• estimation window needs at least {MIN_ESTIMATION_OBSERVATION
• market returns are constant over the estimation window, so b

AI-assisted analysis of HKUDS/Vibe-Trading@80ffdda44c (2026-08-28). Data as JSON: /api/errors/6312548061d23aac. Report an issue: GitHub.