The loss of the Constellation headquarters, then, is no reason to panic, but it does present a good opportunity to take stock of the region's potential and opportunities for economic growth. Although no Baltimore-area companies are on the Fortune 500 now, Legg Mason was just a few years ago, and it could be again. Among up-and-comers, Under Armour has a shot at the Fortune 500 someday. Its revenues last year were about $1.4 billion, well short of the $4.4 billion earned by No. 500 on the list,Seaboard Corp., an agricultural products company headquartered in Merriam, Kan., which is near Kansas City. But given the athletic apparel company's phenomenal growth rate (its revenues increased by more than 38 percent last year), it could crack the list before the decade is out.