Spearhead
02 / Calibration Scorecard

Checking our work — misses included

Every quarter, every probability claim this model made is replayed against realized outcomes. Sample sizes appear next to every number; the misses are printed, not buried.

2025-FY2026-H1WINDOW 2026-01-012026-06-10DATA: FIXTURE | BACKTEST
0.158
Brier score
−2.0%
Brier skill vs base rate
80.8% n=47
80% band, observed
95.7% n=47
95% band, observed
47
Walk-forward residuals
A / Reliability

Claimed probability vs reality

Reliability diagram

0.00.00.20.20.40.40.60.60.80.81.01.0p_hat 0.68 -> observed 1.00 · n=3p_hat 0.76 -> observed 0.76 · n=21p_hat 0.82 -> observed 0.83 · n=23PREDICTED PROBABILITY · n=47OBSERVED FREQUENCY

Interval coverage

nominal 80%80% NOMINAL -> 80.8% OBSERVED · n=47nominal 95%95% NOMINAL -> 95.7% OBSERVED · n=47

Outcomes are leave-one-out band hits, so no residual is ever judged by a quantile it helped set. Base rate 0.809; reference Brier 0.155.

Forecast binMean predictedObserved freqn
0.60.70.6761.0003
0.70.80.7640.76221
0.80.90.8200.82623
B / IPO validation

IPO class — 2026-H1

Held-out outcomes: marks frozen the day before each debut, then compared against the first public print open. Verdicts are interval-honest: a wide band that covers a big move is 'covered', not 'hit'.

CompanyIPOFinal mark80% intervalIPO openError vs openLast-print baselineVerdict
Cerebras Systems2026-05-14$8.1B[$3.8B – $17.1B]$70B−88.4%−88.4%MISS
Why we publish the misses

5 of the validation cases missed badly — including Circle, Chime, Figma, Klarna, Cerebras Systems. Each one is a case where public prints alone were stale or wrong, which is precisely the gap market-derived inputs close. Read the case study →

C / Model disclosure

Every fitted constant, in the open

Model

  • Recency half-life: 90d — selected by walk-forward MAPE: 90d → 39.9% · 180d → 43.0% · 270d → 44.5%
  • Conformal quantiles: q80 = 0.646, q95 = 0.991
  • Width rule: band = mark * exp(+/- q * w), w = 1 + 0.25 * staleness_days / 365
  • Confidence rule: clamp(0.45, 0.95, 0.80 + 0.32*(mean_quality - 0.75) - 0.18*min(staleness/730, 1) + 0.04*min(n_inputs, 5)/5)
  • Residual skew: 97.9% of next prints landed above the prior mark — disclosed, not hidden.

Caveats

  • Illustrative backtest on a curated public-events dataset; no live marks are published.
  • Calibration pool is small (n=47 walk-forward residuals pooled across companies and time); pooling weakens the exchangeability assumption behind the conformal guarantee, so coverage is reported empirically.
  • The recency half-life is the model's single fitted constant, selected by walk-forward error on the same window and disclosed in full below.
  • IPO validation is a handful of individually narrated cases, not a statistical sample; misses are published alongside hits.
  • Signed residuals are one-sided in this window (98% printed above the prior mark): private valuations trended up, so the log-symmetric band is conservative on the downside. The skew is published, not hidden.
Scorecard figures are computed from a backtest replay of public events. Indicative valuations, not transactable prices. Underlying assets are illiquid; inputs are limited to publicly reported events with source attribution. Pegasus Three Sixty and SpearHead are an information-only valuation product, do not hold client balances, and do not provide investment recommendations.