Chip Concentration — computed from official holder-distribution data, open formula
"Chip concentration" is one of the most-quoted, least-computed phrases in Taiwan retail investing. We compute it directly from the official weekly holder-distribution filings: an HHI concentration index, mega-holder (1,000+ lot) ratios with weekly deltas, and retail-share changes — every number traceable to the source brackets, with open deterministic formulas.
How it is computed
The official filing buckets shareholders into 15 lot-size brackets. We compute the HHI (sum of squared bracket shares) — the standard academic concentration measure — plus mega-holder ratios and weekly deltas. Every row carries its availability-date stamp: filings settle Friday and publish the following week, so backtest signals only activate after publication.
What we deliberately do not do
We do not publish a concentration leaderboard. Rankings invite the reading that a high rank is worth buying, yet a rising HHI can equally come from share-count changes, pledged shares or one custodian reshuffling accounts.
We also do not blend concentration, institutional flow and price momentum into a single composite. Every bracket's raw share and weekly delta stays visible; how you weight them is your choice, not a default we picked for you.