Index: binaries/data/mods/public/gui/common/tooltips.js
===================================================================
--- binaries/data/mods/public/gui/common/tooltips.js
+++ binaries/data/mods/public/gui/common/tooltips.js
@@ -827,6 +827,17 @@
 	});
 }
 
+function getTraderTooltip(template)
+{
+	if (!template.trader)
+		return "";
+
+	return sprintf(translate("%(label)s %(details)s"), {
+		"label": headerFont(translate("Trade gain multiplier:")),
+		"details": template.trader.GainMultiplier.toFixed(2)
+	});
+}
+
 /**
  * Returns an array of strings for a set of wall pieces. If the pieces share
  * resource type requirements, output will be of the form '10 to 30 Stone',
Index: binaries/data/mods/public/gui/reference/common/ReferencePage.js
===================================================================
--- binaries/data/mods/public/gui/reference/common/ReferencePage.js
+++ binaries/data/mods/public/gui/reference/common/ReferencePage.js
@@ -60,6 +60,7 @@
 	getProjectilesTooltip,
 	getSpeedTooltip,
 	getGatherTooltip,
+	getTraderTooltip,
 	getResourceSupplyTooltip,
 	getPopulationBonusTooltip,
 	getResourceTrickleTooltip,
Index: binaries/data/mods/public/gui/session/selection_details.js
===================================================================
--- binaries/data/mods/public/gui/session/selection_details.js
+++ binaries/data/mods/public/gui/session/selection_details.js
@@ -315,6 +315,7 @@
 		getHealerTooltip,
 		getResistanceTooltip,
 		getGatherTooltip,
+		getTraderTooltip,
 		getSpeedTooltip,
 		getGarrisonTooltip,
 		getPopulationBonusTooltip,