Geometric Decay

Decay with a dial: size is divided by rⁱ, so r sets the de-risking rate precisely. It is the decay counterpart to geometric martingale and the right choice when you want to express "reduce exposure at this exact rate" rather than pick a named taper.

Size at level i is r⁻ⁱ. With r near 1 the taper is almost flat; as r approaches 2 the curve converges on halving decay. Total ladder cost is bounded by base × r/(r − 1) regardless of depth.

Below is the wizard's own ladder table and the trading terminal's chart engine, both driven by buildLadderPlan for this mode. Change the level count, spread or target and the rung prices, sizes, capital ramp and chart lines recompute exactly as they would in the grid designer.

Bounded by the geometric sum, so extra levels are nearly free. Capital planning is a single closed-form expression, which makes this the easiest decay mode to reason about at arbitrary depth.

Read the cost vs 5 levels column as the escalation test. A flat ladder doubles when the depth doubles; anything materially above that is a curve whose coverage has to be bought rather than simply configured.

With every rung filled, the volume-weighted average entry is 97.18 against a base of 100 and a deepest rung of 90.00 — so the average sits 28% of the way down the covered range. Getting back to flat from the bottom therefore needs a 7.97% bounce, against 5.00% for a flat ladder of the same depth — 2.97% more work.

Divides by a constant ratio each level, so the decay rate is a dial: r near 1 decays slowly, larger r approaches the halving mode.

The last row is the metric that separates modes. Profit for a full cycle is the target percentage of deployed capital in every mode, so it cannot discriminate. What differs is how much capital has to sit reserved to earn one shallow cycle: this mode reserves 1.97× base to collect 33.9 bps of it when the first rung completes.

Trends where you want a specific, auditable de-risking profile — for instance matching the taper to an instrument's historical continuation probability.

Divides by a constant ratio each level. r closer to 1 decays slowly, larger r decays fast (toward the halving mode). Lets you dial capital protection precisely. Floored at 1 lot.

Minimal capital risk. The trade-off is participation, and r controls exactly how much of it you give up.

This is the product's grid backtester, not a summary of one. It fetches public candles for the instrument you pick, rebuilds the ladder anchored on the first candle of the window, then applies the engine's own fill, take-profit, refill and stop-loss rules bar by bar. The caveat block inside the panel is part of the output — read it before trusting a number.

First the arithmetic, then the market. The table below is computed from the size curves alone; the sweep underneath replays every one of those ladders over the same real candle window, with grid_mode as the only variable.

• Trends where you want a precise, tunable de-risking curve.
• You need the worst case to be a closed-form number at any depth.

• You want the deepest rungs to carry real size.
• The configuration will be edited without re-reading what r does to participation.

• r = 1.1–1.3 keeps a real ladder; r ≥ 1.8 is effectively halving decay with extra steps.
• Because cost is bounded, depth is the cheap dial and r is the meaningful one.

This mode is parametric. The wizard and the settings panel show only the dial(s) it actually uses, and changing one is a structural edit — the resting ladder is cancelled and re-placed at the new sizes.

• Watch how quickly executed size hits the one-lot floor — beyond that point extra levels add coverage but almost no averaging.
• Track realised cycles per day. Decay curves earn from frequency, so a falling cycle count is the signal that the market has left the window.
• Check the gap between average entry and mark. Decay curves keep it wide by design, so recovery expectations must be set from it, not from hope.

1. 1
   Over-tapering

   A high r collapses the ladder to the opening position plus a rounding error, which is rarely the intent.
2. 2
   Floor interaction

   The floor truncates the taper wherever it lands, so two different r values can produce the same live ladder. Verify in the plan table.

• Spread sets how fast the ladder consumes depth. Widening it buys coverage for the same level count at the cost of fewer fills.
• Target sets what each cycle books. Below round-trip fees plus slippage, a grid is a fee generator regardless of the size curve.
• The stop loss is the only bound on the tail. Without it, the curve's worst case is whatever the market does, not what you planned.

1. 1
   What is the total cost formula?

   base × r/(r − 1) in the limit — so r = 1.5 caps the whole ladder at about three base lots no matter how many levels you add.

• Sizes and capital: levelMultiplier / gridModeCurve in lib/grid/gridModes.ts, mirrored from grid_modes.hpp and the Python engine's lot calculator.
• Rung and exit prices, capital ramp, init targets and the stop line: buildLadderPlan — the same builder the wizard and grid designer use.
• Backtest fills, cycles and P&L: runBacktest / runBacktestSweep over public broker candles, applying the engine's fill, exit, refill and stop rules.
• Price charts: the trading terminal's chart engine, with the ladder drawn through its own price-line API.

• 1.Grid Modes — Overview — The full taxonomy and how to choose
• 2.Anti-Martingale family — What every curve in this family has in common
• 3.Capital Allocation — Sizing an account to a Geometric Decay ladder
• 4.Stop Loss — Bounding this curve's tail
• 5.Reading the Ladder Plan — Verifying the curve before deploying
• 6.Grid Structure — Levels, init batch and base size