Richard’s personal website: quantitative research, market data, open-source tools and investing.https://runchengxie.github.io/enhttps://runchengxie.github.io/en/blog/buffett-airline-investments/https://runchengxie.github.io/en/blog/buffett-airline-investments/Buffett invested in U.S. airlines on two separate occasions. The first was in 1989, when he bought convertible preferred stock in USAir, later renamed US Airways. The second began in 2016, when he…Fri, 11 Sep 2026 00:00:00 GMTInvestingBuffettCase StudiesInvestment Failureshttps://runchengxie.github.io/en/blog/irish-banks-failed-investment/https://runchengxie.github.io/en/blog/irish-banks-failed-investment/Berkshire spent $244 million on two Irish bank stocks in 2008; their year-end value was just $27 million. Buffett acknowledged misjudging their apparent cheapness. The year-end marks illustrate how…Wed, 01 Apr 2026 00:00:00 GMTInvestingBuffettCase StudiesInvestment Failureshttps://runchengxie.github.io/en/blog/tesco-failed-investment/https://runchengxie.github.io/en/blog/tesco-failed-investment/Buffett had concerns about Tesco's management in 2013 but sold only part of the holding. As operating and accounting problems worsened, Berkshire ultimately recorded an approximately $444 million…Tue, 31 Mar 2026 00:00:00 GMTInvestingBuffettCase StudiesInvestment Failureshttps://runchengxie.github.io/en/blog/dexter-shoe-failed-investment/https://runchengxie.github.io/en/blog/dexter-shoe-failed-investment/Buffett acquired Dexter Shoe with Berkshire shares in 1993 and later acknowledged misjudging its competitive advantage. As the business lost its value, the Berkshire shares paid for it continued…Mon, 30 Mar 2026 00:00:00 GMTInvestingBuffettCase StudiesInvestment Failureshttps://runchengxie.github.io/en/blog/conocophillips-failed-investment/https://runchengxie.github.io/en/blog/conocophillips-failed-investment/Buffett increased Berkshire's ConocoPhillips position near the peak in energy prices in 2008 without anticipating the sharp second-half decline. He subsequently acknowledged in the shareholder…Sun, 29 Mar 2026 00:00:00 GMTInvestingBuffettCase StudiesInvestment Failureshttps://runchengxie.github.io/en/blog/marshall-wells-failed-investment/https://runchengxie.github.io/en/blog/marshall-wells-failed-investment/Marshall-Wells's low valuation attracted the young Buffett, but subsequent operating decline weakened the appeal of the discount. Available interviews and secondary archival research do not…Sat, 28 Mar 2026 00:00:00 GMTInvestingBuffettCase StudiesInvestment Failureshttps://runchengxie.github.io/en/blog/philadelphia-reading-turning-point/https://runchengxie.github.io/en/blog/philadelphia-reading-turning-point/Today, let's discuss a case that is important for understanding the evolution of Buffett's investing: Philadelphia & Reading, or P&R.Thu, 26 Mar 2026 00:00:00 GMTInvestingBuffettCase StudiesCigar-Butt Investinghttps://runchengxie.github.io/en/blog/union-street-railway-case-study/https://runchengxie.github.io/en/blog/union-street-railway-case-study/Union Street Railway traded below its cash-like assets and later distributed $50 per share. Valuing the case requires distinguishing freely available cash from restricted deposits; realizing the…Wed, 25 Mar 2026 00:00:00 GMTInvestingBuffettCase StudiesCigar-Butt Investinghttps://runchengxie.github.io/en/blog/dempster-mill-case-study/https://runchengxie.github.io/en/blog/dempster-mill-case-study/Buffett bought Dempster Mill below his conservative asset valuation. After taking control, he brought in Harry Bottle to improve operations and convert inventory and other assets into cash, making the…Tue, 24 Mar 2026 00:00:00 GMTInvestingBuffettCase StudiesCigar-Butt Investinghttps://runchengxie.github.io/en/blog/sanborn-map-case-study/https://runchengxie.github.io/en/blog/sanborn-map-case-study/Sanborn Map's securities were worth more than the company's market capitalization. Buffett bought shares and helped arrange an exchange through which shareholders received part of those assets,…Mon, 23 Mar 2026 00:00:00 GMTInvestingBuffettCase StudiesCigar-Butt Investinghttps://runchengxie.github.io/en/blog/buffett-selects-rather-than-transforms/https://runchengxie.github.io/en/blog/buffett-selects-rather-than-transforms/Bowen, Rajgopal and Venkatachalam find that Berkshire's listed investments often already match some of Buffett's publicly stated principles before purchase. Evidence of further changes after…Sat, 21 Mar 2026 00:00:00 GMTInvestingBuffettPaper ReviewsCorporate Governancehttps://runchengxie.github.io/en/blog/why-buffett-is-still-hard-to-copy/https://runchengxie.github.io/en/blog/why-buffett-is-still-hard-to-copy/Hou and coauthors find that q-factor models do not fully explain Berkshire's historical excess returns. This concerns model explanatory power and does not directly evaluate every quantitative fund's…Fri, 20 Mar 2026 00:00:00 GMTInvestingBuffettPaper ReviewsAsset Pricinghttps://runchengxie.github.io/en/blog/overconfidence-about-buffett/https://runchengxie.github.io/en/blog/overconfidence-about-buffett/Hughes, Liu and Zhang study Berkshire's holdings disclosures from 1980 to 2006 and find that prices continue adjusting afterward. Their historical evidence makes copying returns and the…Thu, 29 Jan 2026 00:00:00 GMTInvestingBuffettPaper ReviewsMarket Behaviorhttps://runchengxie.github.io/en/blog/the-other-side-of-buffett/https://runchengxie.github.io/en/blog/the-other-side-of-buffett/AQR's Buffett's Alpha connects Berkshire's historical returns with its holdings and financing. The researchers find that inexpensive leverage and a preference for high-quality businesses explain a…Tue, 27 Jan 2026 00:00:00 GMTInvestingBuffettPaper ReviewsLeverage and Qualityhttps://runchengxie.github.io/en/blog/buffett-and-multi-factor-research/https://runchengxie.github.io/en/blog/buffett-and-multi-factor-research/Multifactor studies link valuation and profitability to historical average returns. These findings overlap with Buffett's discussions of business quality and purchase price, although the methods and…Mon, 26 Jan 2026 00:00:00 GMTInvestingBuffettPaper ReviewsQuantitative Research