xbrl-fallbackslisted

# 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'