Copying top investors after their 13Fs go public — what our five-year backtest showed
We tested a simple question: what would have happened if you copied a manager’s disclosed holdings **only after each 13F became public?**
We picked 10 widely followed investors, including Stanley Druckenmiller, David Tepper and Bill Ackman. The test covered September 14, 2021 to September 14, 2026.
The model waited for each filing to become public, bought the disclosed long positions using closing prices after publication, and updated the portfolio when the next filing came out. SPY was measured over the same dates.
|Portfolio copied|Five-year return|
|:-|:-|
|Stanley Druckenmiller’s Duquesne Family Office|\+188.4%|
|David Tepper’s Appaloosa|\+149.5%|
|Gavin Baker’s Atreides|\+131.8%|
|**SPY**|**+82.8%**|
|Berkshire Hathaway|\+77.6%|
|Renaissance Technologies|\+64.0%|
|Citadel Advisors|\+52.5%|
|Pershing Square|\+50.0%|
|Viking Global|\+38.7%|
|Tiger Global|\+18.1%|
|Baupost|\+7.9%|
The part I found more useful was going back through the individual holdings.
Take Druckenmiller. His Duquesne Family Office disclosed a position in **Vertiv in November 2022** and **NVIDIA in February 2023**. Reading those filings would have put both companies on your radar with much of their subsequent rise still ahead. One made the chips; the other supplied power and cooling for data centers.
Atreides offered another way into the same theme through companies such as Coherent and Lumentum, which supply optical components. Following these portfolios could have helped you find businesses behind the AI buildout beyond the names getting most of the headlines.
Of course, those examples are easy to pick now. A filing in 2023 came with a whole list of holdings, and you still had to decide which businesses you understood and what they were worth.
There was also a big difference between the final return and the experience of holding the portfolio. The Atreides copy finished up 131.8%, but at one point it was down **49.7% from its previous peak**. That is a lot to sit through when you are following someone else’s decisions.
For me, the useful next step is to take a newly disclosed holding and ask why the business might be interesting. What is changing? Is demand showing up in revenue and cash flow? What growth and margins does today’s price already require?
A 13F can give you a reason to start that work. By the time the next filing arrives, you should ideally have your own reason for continuing to own the stock.
We also published a longer version of this analysis on Buzzberg, with more examples from individual holdings.
Which managers do you follow, and how do you use their 13F filings in your own research?