CRYPTO20 is a crypto-only index fund that autonomously tracks the top 20 cryptocurrencies in the same way the S&P 500 tracks the top 500 US company stocks. C20 is the fund’s token and represents an investor’s share in the fund. The smart contract allows users to withdraw the net asset value of the token instantly, or it can be freely traded on exchanges at any time, with no exit fees, broker fees or advice fees. Data science was used with extensive backtesting over many rolling windows to determine the fund hyperparameters, asset weighting allocation and rebalancing periods. Holding the perfect, data science driven proportions of the top 20 cryptocurrencies by market cap, with autonomous weekly rebalancing, is now possible by holding a single token.