After moving to New York City and starting my first full-time job, I found myself reading a lot about personal finance and investing. This was mostly to learn what to do with my next paycheck and avoid making stupid decisions, but it also helped me create a reliable, evidence-based financial plan that I simply didn't have to worry about all the time (but could still yap about endlessly).
My current investing philosophy involves a classic three-fund portfolio, which aims to provide broad diversification, low costs, and tax efficiency, all while outperforming the vast majority of individual and professional investors over long time horizons.
While rebalancing this type of portfolio is seemingly simple, there are important considerations, including tax-efficient fund placement and fund limitations in certain accounts (such as an employer 401(k)), to name a few. After I'd calculated the rebalancing trades by hand on two separate occasions, correcting several mistakes in the process, I realized I needed a more robust solution.
Hence, Three-Fund Rebalance was born: a CLI that, given an investor's target asset allocation, rebalancing bands, and account holdings, computes the trades needed to rebalance their three-fund portfolio across multiple accounts. If they enter cash in any of their accounts, the tool suggests trades to fully invest it and approximate their targets.
Some notable design decisions include ingesting account holdings via user inputs. In my experience, this is much faster than waiting for brokerages to publish account holdings to Plaid, for example, which often occurs only once daily. In addition, the tool collects no cost basis data and uses heuristics to determine asset location, both of which make it simpler and more accessible.
If Three-Fund Rebalance serves your needs, or you're willing to play around with it, I'd love for you to use it and share your thoughts! I'm definitely interested in actively maintaining it to better serve others with an investing style similar to mine, so your feedback will not go unnoticed.
And if you're looking to learn more about these topics, I'd highly recommend the following resources. They've personally helped improve my financial literacy:



