diff --git a/src/ac/ed/lurg/country/GlobalPrice.java b/src/ac/ed/lurg/country/GlobalPrice.java
index 29c85f29b161aa2dd6505a4ef4525c7abbdd09dd..364758ae63e60d9e4e654b1652aab80cb2c53335 100644
--- a/src/ac/ed/lurg/country/GlobalPrice.java
+++ b/src/ac/ed/lurg/country/GlobalPrice.java
@@ -34,14 +34,14 @@ public class GlobalPrice {
 		return exportAmount;
 	}
 
-	public GlobalPrice createWithUpdatedMarketPrices(double imports, double exports, boolean adjustPrice, double stockLevel) {
+	public GlobalPrice createWithUpdatedMarketPrices(double imports, double exports, boolean adjustPrice) {
 		if (imports > 0 || exports > 0) {
 			double ratio;
 
 			if (imports > exports)
-				ratio = (imports-exports)/stockLevel;
+				ratio = (imports-exports)/imports;
 			else
-				ratio = (imports-exports)/stockLevel;
+				ratio = (imports-exports)/exports;
 
 			double adjustment = adjustPrice ? Math.exp(ratio * ModelConfig.MARKET_LAMBA) : 1.0;
 			return new GlobalPrice(exportPrice * adjustment, imports, exports);