Portfolio calculators
Portfolio arithmetic is mostly a question of what you compare against. A return means little without the risk taken to reach it, and the risk measures here each answer a slightly different question: total variability, downside only, or how much of the movement was the market’s rather than yours.
Portfolio Rebalancing CalculatorThe trades that return a portfolio to its target weights, with a band so small drifts are left alone and an option to rebalance with new money instead of selling. Selling to rebalance realises gains, which is a cost the drift often does not justify.Asset Allocation by Age CalculatorA starting allocation from age, horizon and how you behave in a fall. The age rules are a heuristic and nothing more, so the page shows what the rule gave before the adjustment and what moved it.Weighted Portfolio Return CalculatorThe weighted return of a portfolio, and how much of it each holding actually produced. Averaging the returns of the holdings equally is the common mistake and it flatters small winners badly.Sharpe Ratio CalculatorReturn per unit of risk, from a return series or from summary figures. The Sharpe ratio treats a good month and a bad month as equally risky, which is its central limitation and the reason the Sortino ratio exists.Sortino Ratio CalculatorThe Sharpe ratio with only downside volatility in the denominator. Where a strategy has occasional large gains the two ratios diverge sharply, and that gap is the point of the measure.Beta and Alpha CalculatorBeta and Jensen alpha from a return history, with the R squared that says whether the beta means anything. A beta fitted against a benchmark the asset barely tracks is a number without content, and the fit statistic is the only way to see that.Return Volatility CalculatorVolatility and Sharpe ratio from a series of returns. Volatility scales with the square root of time, so monthly volatility annualises by multiplying by the root of twelve rather than by twelve.Asset Correlation CalculatorCorrelation between two return series and what it does to a portfolio. Any correlation below one reduces portfolio volatility below the weighted average, which is the entire mathematical case for diversification.