diff --git a/frontend/src/components/LeftoverMapPlot.tsx b/frontend/src/components/LeftoverMapPlot.tsx
index 9f63b5d5e..3e91dbde4 100644
--- a/frontend/src/components/LeftoverMapPlot.tsx
+++ b/frontend/src/components/LeftoverMapPlot.tsx
@@ -30,6 +30,7 @@ import {
 import {
   formatLeftoverMapPlotAxisSingular,
   leftoverMapComparePlotAxisBadge,
+  leftoverMapComparePlotTickAxisBadge,
   leftoverMapPlotTickAxisBadge,
   leftoverSingularForAxis,
   LEFTOVER_MAP_COMPARE_PLOT_AXIS_SINGULAR,
@@ -362,20 +363,23 @@ export function LeftoverMapPlot({
             {leftoverMapPlotAxisText(2, leftoverMapAxes, variant)}
           </text>
           {layout.ticks.map((tick) => {
+            const singular = leftoverSingularForAxis(leftoverMapAxes, tick.axis);
             const reportTickBadge =
               variant === "report"
-                ? leftoverMapPlotTickAxisBadge(
-                    tick.axis,
-                    tick.label,
-                    leftoverSingularForAxis(leftoverMapAxes, tick.axis),
-                  )
+                ? leftoverMapPlotTickAxisBadge(tick.axis, tick.label, singular)
+                : null;
+            const comparisonTickBadge =
+              variant === "comparison"
+                ? leftoverMapComparePlotTickAxisBadge(tick.axis, tick.label, singular)
                 : null;
             const tickAriaLabel =
               variant === "comparison"
-                ? `${t(LEFTOVER_MAP_COMPARE_PLOT_LABEL)}: ${tf(LEFTOVER_MAP_PLOT_TICK, {
-                    axis: tick.axis,
-                    value: tick.label,
-                  })}`
+                ? comparisonTickBadge !== null
+                  ? tf(comparisonTickBadge.template, comparisonTickBadge.values)
+                  : `${t(LEFTOVER_MAP_COMPARE_PLOT_LABEL)}: ${tf(LEFTOVER_MAP_PLOT_TICK, {
+                      axis: tick.axis,
+                      value: tick.label,
+                    })}`
                 : reportTickBadge !== null
                   ? tf(reportTickBadge.template, reportTickBadge.values)
                   : tf(LEFTOVER_MAP_PLOT_TICK, { axis: tick.axis, value: tick.label });
diff --git a/frontend/src/leftoverMapPlotAxisSingular.ts b/frontend/src/leftoverMapPlotAxisSingular.ts
index 273b15244..16423ddad 100644
--- a/frontend/src/leftoverMapPlotAxisSingular.ts
+++ b/frontend/src/leftoverMapPlotAxisSingular.ts
@@ -30,6 +30,9 @@ export const LEFTOVER_MAP_COMPARE_AXIS_SHARE =
 export const LEFTOVER_MAP_PLOT_TICK_SINGULAR =
   "leftover-map axis {axis} tick {value} σ {singular}";
 
+export const LEFTOVER_MAP_COMPARE_PLOT_TICK_SINGULAR =
+  "leftover map comparison graphic leftover-map axis {axis} tick {value} σ {singular}";
+
 export type LeftoverMapPlotAxisSingular = {
   axis_index: LeftoverMapAxis["axis_index"];
   leftover_singular_value?: LeftoverMapAxis["leftover_singular_value"] | null;
@@ -150,3 +153,19 @@ export function leftoverMapPlotTickAxisBadge(
     values: { axis: axisIndex, value: tickLabel, singular },
   };
 }
+
+/** Project finite persisted σ onto one comparison-graphic tick without inventing share evidence. */
+export function leftoverMapComparePlotTickAxisBadge(
+  axisIndex: number,
+  tickLabel: string,
+  leftoverSingular: number | null | undefined,
+): LeftoverMapCompareAxisBadge | null {
+  const singular = formatLeftoverMapPlotAxisSingular(leftoverSingular);
+  if (singular === null) {
+    return null;
+  }
+  return {
+    template: LEFTOVER_MAP_COMPARE_PLOT_TICK_SINGULAR,
+    values: { axis: axisIndex, value: tickLabel, singular },
+  };
+}
diff --git a/tests/test_grouping_comparison_graphic_tick_singular_contract.py b/tests/test_grouping_comparison_graphic_tick_singular_contract.py
new file mode 100644
index 000000000..da559bf74
--- /dev/null
+++ b/tests/test_grouping_comparison_graphic_tick_singular_contract.py
@@ -0,0 +1,37 @@
+"""Executable contract for comparison-graphic tick singular-value captions."""
+
+from pathlib import Path
+
+
+ROOT = Path(__file__).resolve().parents[1]
+SINGULAR_SOURCE = ROOT / "frontend" / "src" / "leftoverMapPlotAxisSingular.ts"
+PLOT_COMPONENT_SOURCE = ROOT / "frontend" / "src" / "components" / "LeftoverMapPlot.tsx"
+
+
+def test_comparison_graphic_tick_keeps_persisted_singular_value_without_share() -> None:
+    """A comparison tick may name valid persisted σ even when axis share is absent."""
+    assert SINGULAR_SOURCE.exists(), "singular-value axis helper is missing"
+    source = SINGULAR_SOURCE.read_text(encoding="utf-8")
+
+    assert "leftoverMapComparePlotTickAxisBadge" in source
+    assert "leftover map comparison graphic leftover-map axis {axis} tick {value} σ {singular}" in source
+
+
+def test_comparison_graphic_consumes_tick_singular_projection() -> None:
+    """The buyer-visible comparison graphic must consume its persisted-σ tick projection."""
+    source = PLOT_COMPONENT_SOURCE.read_text(encoding="utf-8")
+
+    assert "leftoverMapComparePlotTickAxisBadge" in source
+    assert "tf(comparisonTickBadge.template, comparisonTickBadge.values)" in source
+
+
+def test_comparison_graphic_tick_does_not_infer_sigma_or_share() -> None:
+    """Invalid σ falls back to the comparison tick and tick captions never synthesize share."""
+    assert SINGULAR_SOURCE.exists(), "singular-value axis helper is missing"
+    source = SINGULAR_SOURCE.read_text(encoding="utf-8")
+
+    assert "formatLeftoverMapPlotAxisSingular" in source
+    assert "Number.isFinite" in source
+    assert "Math.sqrt" not in source
+    tail = source.split("leftoverMapComparePlotTickAxisBadge", 1)[-1][:1600]
+    assert "leftover_share" not in tail