Methodology

Data Sources

All portfolio data is manually maintained in JSON files within this repository:

• entries.json - Weekly trading activity and contributions
• holdings.json - Current portfolio positions and market prices
• benchmarks.json - S&P 500 weekly closes and HISA rate

Return Calculations

Time-Weighted Return (TWR)

Measures portfolio performance independent of cash flows. Calculated by linking periodic returns, effectively showing how well the investment strategy performed.

Money-Weighted Return (IRR)

Internal Rate of Return considering the timing and size of cash flows. Calculated using Newton-Raphson method with bisection fallback.

Benchmark Calculations

HISA Benchmark (3% APY)

Each weekly deposit is treated as a cash flow into a High-Interest Savings Account earning 3% annually, compounded daily using a 365-day basis:

S&P 500 Dollar-Cost Averaging

Each weekly deposit is treated as purchasing S&P 500 index units at that week's closing level. The accumulated units are then marked to the latest index level.

Limitations

• Market prices may be delayed or approximated
• Historical price data may be incomplete
• Currency conversion not applied (CAD/USD mixed)
• No adjustment for dividends or distributions
• Benchmark data updated manually weekly

Reproducing Results

All calculations are implemented in /lib/math.ts and can be independently verified. The complete data set and calculation logic are open source in this repository.