diff --git a/frontend/src/utils/ChartManager.ts b/frontend/src/utils/ChartManager.ts
index dc8fa00..0022566 100644
--- a/frontend/src/utils/ChartManager.ts
+++ b/frontend/src/utils/ChartManager.ts
@@ -897,8 +897,11 @@ export class ChartManager {
           const fallbackColor = config.type === 'OBV' && plotDef.id === 'plot0'
             ? (regPlot?.color ?? '#2196F3')
             : (regPlot?.color ?? plotDef.color ?? '#2962FF');
+          const resolvedColor = config.type === 'OBV' && plotDef.id === 'plot0'
+            ? '#FFFF00'
+            : resolvePlotLineColor(plotDef.color, fallbackColor);
           series = this.chart.addSeries(LineSeries, {
-            color:            resolvePlotLineColor(plotDef.color, fallbackColor),
+            color:            resolvedColor,
             lineWidth:        (config.type === 'OBV' && plotDef.id === 'plot0'
               ? Math.max(2, plotDef.lineWidth ?? regPlot?.lineWidth ?? 2)
               : Math.max(1, plotDef.lineWidth ?? 1)) as 1 | 2 | 3 | 4,
@@ -910,6 +913,19 @@ export class ChartManager {
             ...(indicatorPriceFormat ? { priceFormat: indicatorPriceFormat } : {}),
           }, pane);
           series.setData(filtered.map(p => ({ time: p.time as Time, value: p.value })));
+          if (config.type === 'OBV') {
+            const p0 = result.plots['plot0'] as PlotData | undefined;
+            const p1 = result.plots['plot1'] as PlotData | undefined;
+            console.error(
+              `[OBV addIndicator] plotDef.id=${plotDef.id}`,
+              '| visible:', isPlotVisible,
+              '| filteredLen:', filtered.length,
+              '| first val:', filtered[0]?.value,
+              '| last val:', filtered[filtered.length - 1]?.value,
+              '| p0.length:', p0?.length, '| p1.length:', p1?.length,
+              '| pane:', pane,
+            );
+          }
           seriesMeta.push({ plotId: plotDef.id, isHistogram: false, color: plotDef.color });
         }
 
@@ -2887,7 +2903,12 @@ export class ChartManager {
         const fallbackColor = entry.type === 'OBV' && pid === 'plot0'
           ? (regPlot?.color ?? '#2196F3')
           : (regPlot?.color ?? plot.color ?? '#aaa');
-        opts['color'] = resolvePlotLineColor(plot.color, fallbackColor);
+        opts['color'] = (entry.type === 'OBV' && pid === 'plot0')
+          ? '#FFFF00'
+          : resolvePlotLineColor(plot.color, fallbackColor);
+        if (entry.type === 'OBV') {
+          console.error(`[OBV applyStyle] pid=${pid} visible=${visible} color=${opts['color']}`);
+        }
         opts['lineWidth'] = entry.type === 'OBV' && pid === 'plot0'
           ? Math.max(2, plot.lineWidth ?? regPlot?.lineWidth ?? 2)
           : Math.max(1, plot.lineWidth ?? regPlot?.lineWidth ?? 1);