GDP is the broadest measure of aggregate economic activity and accounts for almost every sector of the economy. GDP is the broadest measure of economic activity. Analysts use this figure to track the economy's performance because it usually indicates how strong or weak the economy is and that helps predict the potential profit margin for companies. It also helps analysts gauge to see if the economy is accelerating or slowing down. The stock market likes to see strong economic growth because that translates to higher corporate profits.