What we do
13F Radar tracks institutional money flows behind 6,900+ US stocks, distilling 220,000+ quarterly SEC 13F filings into one question: which stocks are being accumulated by a rapidly growing number of institutions?
We don't predict prices or give recommendations. We present one statistically validated pattern — together with every failure case and limitation we know of.
The data
The SEC requires institutions managing over $100M to disclose all US equity holdings within 45 days after each quarter-end (Form 13F). Our database covers 34 quarters since 2017Q4, 224,000 filings and 83 million holding records, reconciled filing-by-filing against the SEC's official index (99.97% complete). ⟲
The core signal: breadth change
Each quarter we compute, for every stock, the change in the number of institutions holding it (d_holders), ranked cross-sectionally. The intuition: one index fund buying on weight rebalance represents one decision; hundreds of unrelated institutions initiating positions in the same quarter represents consensus spreading through professional circles — historically an early-to-mid-stage feature of major rallies.
Why not track share amounts? We tested it: changes in aggregate shares held have no predictive power (slightly negative, likely picking up dilution). What matters is how many are buying, not how much — consistent with academic findings (Chen, Hong & Stein, 2002).
Strict backtest rule: public first, measured second
The biggest trap in 13F analysis is the timeline: March 31 holdings become public in mid-May. Any "return" computed from March 31 prices is paper profit no real investor could capture.
Our rule: signal visibility date = quarter-end + 47 days (statutory deadline plus 2-day buffer). Every return figure on this site is measured from that date onward — returns you could actually have earned.
Backtest results (2018Q2–2026Q1, 31 quarters, 73,106 stock-quarters) ⟲
Holding the top decile of breadth-change each quarter for ~6 months:
| Single stock beats universe | 49.6% — a coin flip |
| Single stock positive return | 58.8% |
| Portfolio beats universe, share of quarters | 22/31 = 71% |
| Portfolio 6-month return | mean +8.0%, median +4.8% |
Read this carefully: the signal does not improve your odds on any single stock — half the names in the basket do nothing special. What it improves is the odds of catching the big winners: returns are heavily right-skewed (mean 8.0% vs median 4.8%), and nearly all excess return comes from a few large rallies caught systematically. Use it as a basket, never as a single bet.
By year, the signal worked in 7 of 8 years. The exception: 2020 — in the post-crash V-recovery, the stocks institutions had dumped hardest bounced hardest. Every trend-following signal fails in that regime. We don't hide this, because it will happen again.
What it caught
Breadth-change percentile on the day the signal became visible (1.000 = strongest in market):
- NVDA, 2023Q1 holdings (visible May 2023): 0.999, +62% over the next 6 months, followed by a two-year run ⟲
- Micron (MU), 2025Q2 (visible Aug 2025): 0.985, +241% over the next 6 months ⟲
- SanDisk (SNDK), Palantir (PLTR): lit continuously from 2025Q3 / 2023Q2 respectively
What it missed (read this)
Tesla, mid-2019: the stock sat at a major bottom while institutions were fleeing — breadth-change percentile 0.016 (near the bottom of the market). The stock rose +290% in the following 6 months. ⟲
This failure defines the signal's boundary: it confirms trends; it does not call bottoms. Fundamentals-driven, progressively accumulated rallies (NVDA/MU-type) get caught early-to-mid. Retail- and squeeze-driven V-reversals (TSLA-2019-type) are structurally invisible to it — it may even read inverted. Do not use it to hunt for washed-out bottoms.
Exit reference: signal extinction
For stocks previously in the top 20% of breadth change, the following quarter's state matters:
| Next-quarter state | Excess return, quarter after |
| Still lit | +1.3% |
| Extinguished, price holding | +0.4% (usually digestion — false alarm) |
| Extinguished AND price falling | -0.4% (-0.9% over 6 months) |
Extinction alone is noise; extinction confirmed by price weakness (our red light) is what statistically precedes underperformance. Micron's two red lights (2018Q3, 2022Q1) both landed near memory-cycle peaks. ⟲
Our limitations (as important as the results)
- Survivorship bias: delisted/acquired stocks drop out of return statistics; historical figures are optimistic. Relative rankings between signals are unaffected; discount the absolute numbers.
- 45-day lag: you see holdings at least six weeks old. This signal earns the middle of trends, never the start.
- Long-only: 13F excludes shorts; hedges may mask true views.
- Quarterly resolution: intra-quarter round trips are invisible.
- Statistics, not causality: a 71% quarterly win rate means losing 29% of the time, with no guarantee the pattern persists.
Our commitment
Within 48 hours of each filing deadline, the quarter's lists are frozen and archived, immutable. When next quarter's data arrives, the previous lists are settled against real returns and published — including the losing quarters. Every historical figure you see here was produced under these rules.
Disclaimer
This site is a statistical organization of public data and does not constitute investment advice. Historical patterns do not predict future results. Invest at your own risk.