Historical Symbols
Historical symbols are instruments that existed at some point in the past and may still have historical market data available, even if they are inactive or delisted today. This includes delisted spot pairs, expired futures contracts, replaced perpetuals, and instruments that changed status over time. Historical symbols are essential for time-consistent research because they represent what was actually tradable then.
Why historical symbols matter in backtesting?
If you build a dataset only from today’s active symbols, you often omit historical symbols that later disappeared. That omission can create survivorship bias and distort cross-sectional metrics like average returns, volatility, or spreads. Including historical symbols via a point-in-time universe makes your backtest reflect the opportunity set that truly existed at each timestamp.
Are historical symbols always delisted?
Not always. “Historical” simply means the symbol existed in the past; it may still be active today. The practical use of the term is to remind you that the symbol list changes over time and must be treated as time-varying.
How do historical symbols relate to survivorship bias?
Survivorship bias happens when you exclude instruments that existed historically but later disappeared. Those excluded instruments often had poor performance or low liquidity, so omitting them can make historical results look better than reality. Using historical symbols as-of each timestamp reduces this bias.
Do you need historical symbols for factor research or only trading backtests?
You need them for any historical cross-sectional analysis where the set of eligible instruments matters, including factor research, index construction, and liquidity studies. If the universe is wrong, the computed “market” distribution is wrong. That can change both conclusions and model parameters.
Real-world example
You analyze liquidity across an exchange from 2019–2024. If you use today’s symbol list, early years will appear to have far fewer pairs and potentially better average spreads. When you include historical symbols that were later delisted, the early-years universe is larger and average liquidity measures change materially.
Historical Symbols
and CoinAPI Market Data API
CoinAPI symbol metadata includes fields that help you identify symbols that are no longer active but still have historical data. Use the per-symbol coverage timestamps to build a point-in-time universe and to constrain historical trades/quotes/order-book requests to the period where data exists.