Grid Trading, Shannon’s Demon, and Position Rebalancing

Summary

The document explains grid trading as repeated buying during declines and selling during advances, with portfolio rebalancing used to harvest price fluctuations. Its central example, attributed to Shannon’s Demon, splits capital equally between shares and cash and restores that balance after price moves. It uses a price that doubles and then halves to illustrate how rebalancing can leave the portfolio above its starting value, and connects the allocation choice to the Kelly criterion and compounded returns.

The article also derives a grid example from assumed symmetric log returns, then estimates gains under those assumptions. These calculations are illustrative rather than empirical evidence. The proposed results depend on the return distribution, repeated oscillation, and maintaining the target allocation; transaction costs, taxes, and execution are not incorporated. The document acknowledges that persistent one-way moves and grid-boundary failures can undermine the approach, though it does not rigorously quantify those risks. Its claims of stable profit therefore should not be treated as generally established.

Key ideas

• Grid trading repeatedly buys lower and sells higher while maintaining a target allocation between cash and an asset.
• Shannon’s Demon illustrates how rebalancing can benefit a portfolio as prices fluctuate, even when price returns compound to the starting level.
• The article relates the target allocation to the Kelly criterion and geometric growth under specified probability and payoff assumptions.
• Its numerical examples rely on assumptions about symmetric log returns and omit transaction costs and other implementation frictions.
• One-way markets and moves outside the chosen grid can weaken or invalidate the strategy.

Tags

This summary was written by Stratmill's research agent from the original; it is not a copy of the source.