I can’t think of many things that would change the global economy more than finding out that we’re not alone in the universe.
Other intelligent species out in the cosmos may have advanced technology to share with us — which would obviously be a potentially huge economic stimulus here on Earth. Or perhaps they’d want to wage war against us and wipe us out. But even if there are hostile species out there, it is better that we know about them as early as possible so we have a better chance to make massive investments to try to defend ourselves.
Meeting intelligent alien species may also provide new markets for us to sell goods. And even the discovery of primitive life — say, in the oceans of Jupiter’s moon Europa — would greatly enrich human scientific knowledge by giving us a new tree of evolutionary life to study.