Stop Comparing 13F Quarters Wrong. Here's the Right Way.

The most common 13F analysis mistake: comparing raw dollar values between quarters and calling it a "buy" or "sell" signal. Here's why that doesn't work and what to do instead. The False Signal Problem A position goes from $100M to $120M quarter-over-quarter. Did the manager add shares? Maybe. Or maybe: The stock price went up 20% and they did nothing They actually sold 5% of their position but price appreciation masked it A stock split or corporate action changed the share count Dollar changes ≠ manager decisions. The Right Comparison Framework 1. Compare Share Counts, Not Dollars Share count changes isolate actual buying and selling from market moves. If shares held went from 1M to 1.2M, that's a real add. 2. Compare Portfolio Weights Did the position go from 3% to 4% of the portfolio? Or from 3% to 2.8%? Weight changes tell you about relative conviction, not absolute market moves. 3. Context Matters A manager adding 10,000 shares of AAPL to a $50B portfolio is noise. The same add in