Bitcoin: The Little Rule That Beats the Market

I study a daily rule that sets Bitcoin exposure from two observable inputs: the trend of a foreign-currency basket against the dollar and the deviation of Bitcoin's price from a fixed power-law curve. I construct the basket from the Japanese yen, Chinese yuan and British pound, using Federal Reserve trade weights published at each annual reset. In this paper, the market means Bitcoin buy-and-hold. From January 1, 2014 to November 6, 2026, the rule earned a compound annual growth rate (CAGR) of 70.41%, a Sharpe ratio of 1.46, a maximum drawdown of -51.91% and a final multiple of 941.64 times. Buy-and-hold earned 43.19%, 0.87, -83.62% and 100.63 times. The results are a historical evaluation. Paired 95% bootstrap intervals include zero for the CAGR and Sharpe gaps and exclude zero for the drawdown gap. I selected the currencies and parameters with knowledge of this sample, and the account uses synthetic short positions and omits financing costs. I motivate the rule with the hypothesis that easier global dollar conditions support portfolio demand for Bitcoin. The backtest leaves that channel unidentified, and the rule needs a prospective holdout.