How the Simulator Works

The Portfolio Simulator invests a monthly amount across the mix you choose, using real historical prices, and shows what would have happened.

1
Choose an amount

How much per month, and for how many years.

2
Build your mix

Pick tickers and set what share of each purchase goes to each one.

3
Run against history

The simulation replays real monthly prices and dividends.

4
Explore the result

Summary figures, charts, a month-by-month table, and tax impact.

A few things worth knowing

See detailed methodology

How purchases are made

  • Buys whole shares only, at the monthly high price — a deliberately conservative entry assumption.
  • Unspent cash accumulates per ticker in its own bucket until there is enough to buy the next whole share.
  • If an asset wasn't tradeable in a given month, its share of that month's budget flows to the other assets and resumes the following month.

Share accumulation — worked example

Setup: $1,000/month — 60% Holding A ($250/share), 40% Holding B ($800/share).

  • Month 1: $600 to A → buys 2 shares ($500), carries $100. $400 to B — not enough for a share yet.
  • Month 2: $700 available for A → buys 2 shares, carries $200. $800 for B → buys 1 share, carries $0.

Dividends and interest

  • Dividends are tracked as cash received and are not reinvested back into equities.
  • That cash earns money market interest at the historical FRED federal funds rate, compounded monthly.
  • The MMF benchmark shows what the same total invested would have earned in a money market fund alone.

Deposit growth

The optional annual deposit growth field adds a flat dollar amount each year: year 1 uses the base amount, year 2 adds the growth figure, year 3 adds twice it, and so on.

What the results show

  • Six summary figures — total invested, equity value, dividends received, cash accrual, portfolio balance, and the money market benchmark. Each is clickable for detail.
  • Charts — hover for month-by-month growth and dividend detail.
  • Monthly breakdown table — click any highlighted cell for per-ticker detail.
  • Tax impact — adjust your tax rate to see yearly liability on dividends and interest.
  • Annual returns — pre-tax performance per calendar year.
Open the Portfolio Simulator