How to Compare Passive Giant 13Fs Without Getting Fooled

Don't Compare Dollars, Compare Weights

1. Normalize by AUM
2. Check deviation from benchmark (active share)
3. Look at edges — small positions where passive and active diverge

def active_share(filer_weights, benchmark_weights):
    return sum(abs(fw - bw) for fw, bw in zip(filer_weights, benchmark_weights)) / 2

Full guide: https://13finsight.com/learn/how-to-compare-vanguard-blackrock-state-street-13fs-without-getting-fooled?utm_source=devto&utm_medium=social&utm_campaign=article_ops_0319

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Originally published at 13finsight.com