# Xbrl Fallbacks

> Use when SEC XBRL company-facts data returns 404, is empty, or has sparse coverage — typical for recent FPIs (foreign private issuers), recent IPOs, SPACs, or shell companies. Defines the document hierarchy and extraction rules to recover shares-outstanding data from filing text when structured XBRL is unavailable.

- Skill: `jefrnc/xbrl-fallbacks` (Agent Skill)
- Install (CLI): `npx skillmds@latest add jefrnc/xbrl-fallbacks`
- Raw SKILL.md: https://api.skillmd.com/api/skills/jefrnc/xbrl-fallbacks/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- License: MIT
- Author: jefrnc (https://skillmd.com/u/jefrnc)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/jefrnc/xbrl-fallbacks

---


# XBRL Fallbacks

XBRL coverage is incomplete. Many real issuers — especially the small-cap
universe where dilution analysis matters most — return either 404 or
empty datapoints from `data.sec.gov/api/xbrl/companyfacts/CIK*.json`.
Treating absence of XBRL as absence of data is a quant pipeline bug.
The shares-outstanding number is almost always *somewhere*; just not
in the structured feed.

## Core principle

**XBRL is one source, not the source.** When the structured feed is
sparse or missing, the same datapoint is recoverable by reading the
filing's text — typically the cover page or an early section of the
prospectus. Build the fallback path explicitly into the pipeline; don't
treat XBRL 404 as "no data".

## When XBRL fails (the 404 / empty-set universe)

1. **Recent FPIs** (Foreign Private Issuers). They file F-1, 20-F, 6-K
   in HTML/PDF. XBRL coverage is often delayed, partial, or absent for
   years after IPO. Common in Chinese small-cap IPOs (`-F` suffix CIKs,
   recent listings on Nasdaq Capital Market).
2. **Recent US IPOs** in the first 2 quarters post-listing — 10-Q
   XBRL exists but the cover-page share count may be the only reliable
   datapoint until the second 10-K is filed.
3. **SPACs pre-business-combination.** The shell phase has minimal
   XBRL; cover-page counts on the most recent 10-Q/10-K govern.
4. **Shell companies / OTC issuers** where XBRL is filed late or only
   for the most recent period.
5. **Amended filings (10-K/A, 10-Q/A)** — sometimes don't republish
   XBRL; you have to read the amendment text.

## Fallback hierarchy

When XBRL is missing or stale, search for shares-outstanding in this
order:

1. **Most recent 10-Q cover page** (US issuer) — "As of [date], the
   registrant had [N] shares of common stock, $[par] par value, outstanding."
2. **Most recent 10-K cover page** (US issuer) — same pattern, slightly
   different timing (annual).
3. **Most recent 6-K cover or text** (FPI) — variable format; often
   reports issuance counts within the body. Look for "ordinary shares"
   or "common shares" + "issued and outstanding".
4. **Most recent 20-F cover** (FPI annual) — formal cover-page
   statement near the registrant block.
5. **Most recent F-1 / F-3 / F-3A cover or first page** (FPI registration).
6. **Most recent 424B prospectus supplement cover** — discloses
   pre-offering share count and post-offering count.
7. **Most recent DEF 14A** (proxy) — record-date count, useful as
   a sanity check.
8. **Form 10 / S-1** (if newly registering) — initial count.

The earliest plausible source wins; later sources are sanity checks.
Always record which source was used.

## Extraction patterns (text-based)

Cover-page share-count language is heavily templated. The common forms:

- "As of [date], [N] shares of [class] common stock were outstanding."
- "[N] shares of common stock, par value $[X] per share, are issued
  and outstanding as of [date]."
- "[N] ordinary shares" / "[N] American Depositary Shares (ADSs)"
  representing [M] ordinary shares (FPI ADR structure — keep BOTH
  numbers and note the ratio).
- "[N] Class A common stock and [M] Class B common stock"
  (multi-class issuers — sum carefully or track per-class).
- "issued and outstanding": [N] (table format common in proxies).

Numbers may be expressed with commas, no commas, or scaled
("12.3 million" / "12,300,000"). Always normalize to integer share
count and record the as-of date.

## Multi-class share gotchas

Many small-cap FPIs and biotech reorganizations have multiple share
classes. Treating "common stock outstanding" as a single number can be
wrong by a factor of 2–10x.

- **Class A / Class B**: voting/economic asymmetry — sum for total
  outstanding but track separately for control analysis.
- **Ordinary shares + ADSs**: FPI structure. ADSs trade on the US
  exchange but represent ordinary shares at a ratio (often 1:10 or
  1:50). Float-rotation math must use the ADS-equivalent count, not
  the underlying ordinary share count.
- **Preferred convertible into common**: not currently outstanding as
  common but creates shadow dilution. Note as a separate line.

## Synthetic-tag convention (for pipelines)

When emitting fallback data into a downstream system that expects XBRL
shape, use a synthetic tag namespace to preserve provenance:

```
{
  "tag": "text:SharesOutstanding",
  "value": 23300000,
  "source_form": "424B4",
  "source_accession": "0001213900-24-XXXXXX",
  "as_of_date": "2024-09-15",
  "filed_date": "2024-09-18",
  "confidence": "medium"
}
```

`text:` prefix distinguishes from real XBRL (`us-gaap:`, `dei:`,
`ifrs-full:`). Confidence reflects parsing precision (e.g.,
"high" = direct quote, "medium" = inferred from context, "low" =
calculated from offering deltas).

## Validation rules

1. The fallback datapoint's `filed_date` must obey `lookahead-safety`
   — never use `as_of_date` as the known-date.
2. Cross-check the fallback against ANY available XBRL — even one
   datapoint can confirm the order of magnitude.
3. Sanity-check against the offering history: if the issuer raised
   N shares between two cover-page disclosures, the difference between
   the two counts should be approximately N (modulo buybacks, splits,
   exercises).
4. Flag any fallback as `text:` and surface the source filing in the
   final output — don't silently treat it as XBRL-quality.

## Workflow when XBRL returns 404 or empty

1. Confirm the CIK is correct (most common false-404 cause is a CIK
   typo or unmapped ticker — see `cik-resolution` if available).
2. Pull the issuer's full submissions list:
   `data.sec.gov/submissions/CIK{padded}.json`
3. Walk filings in REVERSE chronological order through the hierarchy
   above (10-Q → 10-K → 6-K → 20-F → F-* → 424B → DEF 14A).
4. Extract the cover-page count from the FIRST filing that has it.
5. For historical analysis, walk forward from the earliest fallback
   datapoint, applying offering deltas (424B / 8-K item 3.02) between
   stamps to maintain a continuous timeline.
6. Tag every fallback datapoint with source attribution and confidence.

## Phrases that should trigger this skill

- "XBRL is empty / missing / 404"
- "no XBRL for ticker X"
- "FPI shares outstanding" / "Chinese small cap shares outstanding"
- "20-F" / "6-K" / "F-1" + share count
- "ADS to ordinary shares ratio"
- "cover page shares"
- "how do I get shares outstanding without XBRL"
- "SPAC shares outstanding"

## What this skill is NOT

This is not a regex library or extractor. It defines the source
hierarchy and validation rules so the LLM (or pipeline) can decide
WHERE to look and HOW to attribute the result. Combine with
`lookahead-safety` for time semantics and `sec-filing-types` for
form-by-form context.