Core Insights - Renowned investor Duan Yongping, who has been "retired" for over 20 years, recently shared his investment philosophy in an interview, emphasizing the importance of understanding companies when buying stocks [2] - Duan believes that while the principle of investing is simple—buying stocks means buying companies—the challenge lies in truly understanding these companies and their business models [2] - He highlighted that even understanding the phrase "buying stocks means buying companies" is difficult, and true comprehension significantly influences investment behavior [2] - Duan noted that not understanding a company does not necessarily equate to not making money, as luck can play a role in investment success [2] Investment Recommendations - Duan suggested investing in the S&P 500 index, indicating that it is likely to yield profits in the long run, although this does not imply a full understanding of the market [3]