berkshire engine
The float mechanism
The insurance float model leverages the temporal mismatch between premium collection and claim payments. This creates a persistent pool of investable capital with negative cost of carry when underwriting operations achieve profitability. The economic dynamics resemble leveraged investing without traditional debt obligations.
What the chart tracks
The visualization tracks three metrics: cumulative portfolio value, investable float magnitude, and aggregate underwriting performance. The model demonstrates how even marginal underwriting margins (0 to 2 percent) generate substantial value through the compounding of float-derived investment returns over extended time horizons.
Key parameters
Float growth rate equals annual premium volume; investment returns compound on the entire float balance; underwriting margin directly impacts cost of capital. The model assumes stable premium flow and consistent investment returns, abstracting from insurance cycle volatility and market fluctuations.
- engine: float(n) = n x annualPremiums; cumulative underwriting = years x premium x margin; investment gain = float x return each year; portfolio = underwriting + investment gains.
- closed-form helpers compoundValue (FV = PV(1+r)^n), cagr ((end/start)^(1/n) - 1), floatContribution, annualUnderwriting and floatCostPercent extracted from the Viewer recurrence.
- calibration: five exact identities (compound value, doubling CAGR, cumulative underwriting, single-year float gain, negative cost of float) checked against analytic targets with zero error.
- six assumptions distinguishing established compounding mathematics from the contested permanent-float and constant-return idealisations.
- research companion on insurance float, the cost of float, and why compounding dominates the long-run portfolio.