Why follow 13F filings at all
Professional investors spend millions on research. Their 13F filings show, once a quarter, where that research led. You will not get their reasoning or their timing, but you do get a list of the companies they were willing to own in size. Used carefully, that is a high-quality research list. Used carelessly, it is a 45-day-old snapshot that can mislead. If 13Fs are new to you, start with how 13F filings work.
1. Pick the funds worth following
Not every 13F filer is worth tracking. Index-like asset managers own almost everything. High-turnover quantitative funds change their portfolios so fast that a quarter-end snapshot says little. The funds worth following hold concentrated positions for a long time, so each line reflects a decision.
SignalX groups the managers it tracks by style: conviction investors such as Berkshire Hathaway, Baupost, Tiger Global and ARK; activists such as Pershing Square, Icahn, Third Point and Starboard; quantitative and multi-strategy firms; asset managers; and corporate stakes. Its consensus views use the 17 conviction and activist funds by default.
2. Compare share counts, not dollar values
Classify each position by what happened to the number of shares between quarters: new, added, trimmed, exited or held. Dollar values move with the stock price and will mislead you whenever a stock has moved a lot. SignalX treats a change of more than 5% in share count as an add or trim.
3. Look for consensus
One fund buying is an opinion. Several independent funds buying the same stock in the same quarter is a pattern worth investigating. Here is what the 17 tracked conviction and activist funds did in the second quarter of 2026.
Q2 2026 · funds that opened or added (of 17 tracked)
- Alphabet GOOGL+$18.0B est.6 of 17
- SpaceX +$1.1B est.5 of 17
- Amazon AMZN+$821M est.4 of 17
- Cerebras Systems +$865M est.3 of 17
- Intel INTC+$384M est.3 of 17
Q2 2026 · funds that trimmed or exited
- Microsoft MSFT−$560M est.5 of 17
- Meta Platforms META−$310M est.4 of 17
- Taiwan Semiconductor TSM−$1.5B est.4 of 17
4. Weigh conviction
A new position worth 0.1% of a fund's portfolio is a toe in the water. One that goes straight to 2% or more is a deliberate bet. The conviction matrix below plots each stock by how many funds hold it and how many were net buyers, so you can see crowded ideas, emerging ones and the ones being abandoned.
5. Check fresher filings
Because 13Fs are slow, use faster filings to see what happened since quarter end. A fund that crosses 5% of a company must file a Schedule 13D or 13G, now within five business days for activists and passive investors. Insider purchases appear on Form 4 within two business days. Our guide to 13D vs 13G explains both.
Common pitfalls
- Treating options as stock. A large put position may be a hedge, and calls are a leveraged bet. SignalX excludes option rows from its consensus.
- Ignoring the lag. A fund may have sold a position before its 13F was even filed.
- Mistaking corporate actions for buying. Spin-offs and CUSIP changes can make a position look new.
- Forgetting what is missing. No shorts, no cash and few foreign holdings means a 13F can make a fund look more bullish than it is.