A simple rule-based rotation: if SPY’s 10-day volatility is above 3, invest entirely in TLT (long-term Treasuries); otherwise invest entirely in SPY (large-cap stocks). No regular rebalancing; switches only when the rule triggers; two-asset, one-position-at-a-time approach.

- What you need to know: SPY is an ETF that aims to mirror large US stocks. TLT is an ETF that holds long-term US government bonds. The strategy looks at SPY’s recent price behavior to gauge volatility, using the last 10 trading days. If that volatility measure is above a threshold of 3, it switches to TLT (so you’d own bonds). If it’s not above 3, it switches to SPY (stocks). - How it decides: compute SPY’s 10-day standard deviation of returns. If this number > 3, choose TLT; otherwise choose SPY. - How much you hold: in practice, you hold 100% in the chosen asset (the “wt_cash_equal” wrapper indicates equal weighting, but since there’s only one asset in a branch, that means full allocation to that asset). - How often it can change: the strategy uses a single rule with no regular rebalancing. It could switch when the condition flips, but there’s no calendar-based rebalance. - What you’re exposed to: SPY gives you exposure to large US stocks; TLT gives you exposure to long-term U.S. government bonds. The approach is intended to tilt toward bonds in volatile markets and toward stocks in calmer markets, but it’s a very small, two-asset system with potential for whipsaws and no diversification beyond the pair. - Practical caveats: this is a backtested, overfit-looking rule. Real-world results can differ due to costs, taxes, liquidity, and regime changes.

Simple risk-on/risk-off rule delivers comparable gains to the S&P 500 with stronger risk-adjusted performance: oos Sharpe 1.46 vs 1.43, beta ~0.96, similar drawdown, transparent rules, and low turnover.