Retail–Mega Divergence — who is accumulating? Computed from official weekly filings
"Big holders quietly buying while retail sells" is one of the most popular narratives in Taiwan investing — usually backed by a screenshot. We compute it: rolling N-week deltas of the mega-holder (1,000+ lot) share vs the retail share, straight from the official weekly holder-distribution filings, flagging divergence when the two move in opposite directions. Open formulas, deterministic, availability-date stamped.
How it is computed
The official filing buckets holders into 15 lot-size brackets weekly. We define 1,000+ lots as mega holders and small brackets as retail, compute rolling N-week (default 12) deltas for both, and flag divergence when directions oppose. Every row carries its availability-date stamp — filings publish the week after settlement, so backtest signals only activate after publication. Honest limit: bracket shifts can come from CB conversion or corporate actions, not just accumulation.
Divergence is not a stock pick
Mega-holder share can rise because of convertible-bond conversion, an employee shareholding trust, or a bracket shift after an ex-dividend adjustment. None of those is accumulation, and all of them look like divergence in the filing.
The indicator quantifies how much the ownership structure moved. Whether that movement is meaningful is your call, and we publish no recommendation either way.