An Introduction to Retrieving Historical Security Prices with GOOGLEFINANCE and STOCKHISTORY Historical price data plays a central role in security trading analytics. Most trading and analytical models rely on past prices to generate signals about when to buy or sell. With historical prices available, analyst can backtest strategies, evaluate return patterns, and measure volatility across different timeframes. Whether you are calculating exponential moving averages with different period lengths, comparing moving averages to daily or weekly closes, generating MACD lines and histograms, or computing Relative Strength indicators, historical prices are the underlying data source. Historical data across different asset classes and time horizons also helps reveal broader market behavior. Long ‑ term price series allow analysts to estimate growth rates for various asset categories, while cross ‑ asset comparisons can highlight regime shifts and test how well strategies hold up under cha...