Investors with taxable portfolios sometimes delay the sale of appreciated stock to defer capital gains taxes. While this strategy does help to reduce taxes, it can cause the portfolio to become more concentrated over time, leading to higher overall volatility and lower long-term returns. This...

Stock investors who are charitable donors can minimize capital gains taxes and improve portfolio diversification by donating their most appreciated shares instead of cash, and then investing the freed-up cash in the portfolio's least-weighted stocks. The charity is indifferent to the donation...

Recommender systems often recommend several products to a user at the same time, but with little consideration of the relationships among the recommended products. We argue that relationships such as substitutes and complements are crucial, since the utility of one product may depend on whether...