1) This can be a good strategy, but I'd advise caution. Because there's a delay between when positions are established and 13-Fs are released, it's better to follow a long-term investor rather than a short-term trader.

13F filings can be a great place to source investment ideas. It can be intimidating to pick a portfolio from thousands of stocks. By seeing what legendary investors are holding, it's possible to prescreen several ideas for further research.

I would avoid using AI to make specific stock picks at all costs. So many AI models are based on patterns in text and words. But investing is a numbers game.

2) Some Wall Street legends have published details of their methodology. For example, Joel Greenblatt's method is detailed in "The Little Book that Beats the Market". It involves ranking stocks based on two financial metrics. While this sounds simple enough, it is not so straightforward in practice. First of all, financial data is notoriously messy. Generally you get what you pay for, and professionals spend thousands per year. Second, even the best approach become stale and require updating.

3) I've always resonated with the investing style of Peter Lynch. With so much concentration in the S&P 500, now is the best time to find opportunities in disregarded stocks like he did. While he is no longer as active as in his heyday, Lynch detailed his investing approach in his writing. Copying an investing approach is not as straightforward as copying portfolio trades. But Lynch has shown that outperforming doesn't require tremendous resources like hiring a team of analysis.

4) When browsing 13Fs, try to see when a position was established. It may not good to simply look at the latest filing to copy a portfolio. Many positions could be old and are no longer ripe for new investment.