How does the stocks on a trade portal work?

Quick question, are the stocks on a portal global meaning every trade portal shares the same stocks, or are only trade portals on the same server sharing the same stocks?

The stocks are global.
http://blockmarket.theblockheads.net/

Is the link updated live?

Jet packs sure are cheap today!

If I recall correctly, there isn’t a direct impact on the global stocks from one single trade portal. You’ll see the price change immediately on your trade portal for each purchase or sale you make. That change will have a slower effect on other trade portals on that server and then globally. And custom servers have no external impact or influence, but the prices will be affected by the global prices at large.