Overview
The Backtester is a portfolio simulation tool. You define a basket of stocks or exchange-traded funds, a weighting scheme, a date range, and a set of rules for rebalancing, dividends, and trading costs. The tool then replays that strategy day by day through historical market prices and shows how it would have performed. It is a "what would have happened" tool. It does not predict the future. It reconstructs the past for a portfolio you describe. This page explains what the Backtester is for, what it produces, and where each part is documented in detail. The tool is available to Free, Pro Lite, and Pro accounts.
What it shows
You build a portfolio idea in a five-step form, press Run backtest, and receive a single continuous report. The report covers the parts described in the following sections.
The growth curve and returns
A daily equity curve plots the dollar value of the strategy across the full date range, with headline figures for total return, compound annual growth rate, volatility, the Sharpe ratio, and the maximum drawdown. See Charts and graphs and Results and metrics.
Risk and drawdowns
A drawdown chart, a rolling-stability chart, a daily-return distribution, and a set of risk tiles describe not only the return but the ride: how deep the losses ran, how long recovery took, and how steady the strategy's edge was. See Charts and graphs.
Benchmark comparison
Every run tracks a benchmark ticker over the identical period and folds a full head-to-head into the report, covering relative returns, alpha and beta, capture ratios, and a year-by-year table. See Benchmark comparison.
Dividends, costs, and attribution
The report breaks out dividend income and growth, trading costs and turnover, portfolio concentration, and per-holding attribution, so you can see what drove the result. See Results and metrics.
Transactions and the process log
A full transaction log lists every buy, sell, dividend, and rebalance, and a per-rebalance process log shows what the strategy did on each rebalance date. See Results and metrics.
Inputs
You set the holdings, the weights, the date range, the starting capital, the rebalance rules, the dividend handling, and an optional benchmark, with an Advanced panel for commission, slippage, the rebalance method, drift tolerance, and a dividend tax rate. Every field, its accepted values, and its default are documented in Inputs and settings.
Use cases
- Test a stock or fund basket before investing real money, to see how it would have grown and how rough the ride would have been.
- Compare two or three competing strategies on one chart, with different weights, rebalance schedules, or holdings.
- Stress-test an allocation across past downturns using the crisis-window scorecard and drawdown analysis.
- Study the income profile of a dividend-focused portfolio, including reinvestment compounding and year-over-year dividend growth.
- Audit whether rebalancing actually helped, and whether trading costs are eating returns.
Limitations and disclosures
Results are hypothetical. A backtest reconstructs the past for a portfolio you describe. It is not a prediction, and past performance does not guarantee future results. The simulation uses end-of-day historical prices and the standard cost assumptions you set. It does not model intraday execution, real order fills, or market impact beyond the slippage you provide.
GNG Research provides equity research and educational tools, not investment advice. Nothing on the platform is a recommendation to buy or sell any security. Do your own research and consider your circumstances before making any investment decision.