A Joe Biden presidency in the US is expected to mean significant change for the global economy - but anyone hoping for a sudden overhaul of every Trump policy may be disappointed, as Yahoo Finance UK's Tom Belger explains.As soon as it started to look like Joe Biden was going to be the next US president, stock markets rallied worldwide.But why is that? One thing analysts talk about is predictability.Firms typically hate nothing more than uncertainty. Firms and consumers alike are far more likely to be happy spending money, taking risks and investing in the long-term if they’re not afraid there's big, sudden, unpredictable change looming just around the corner. If you can say one thing about Trump, it's that he's anything but predictable.But he is also a protectionist. He put up barriers to trade with China and other countries, and those barriers plus fear of more to come had a chilling effect on the global economy. He also set back global efforts on threats like climate change.Biden is expected to be a lot more stable and to try to build bridges across the globe. Yet anyone hoping for a sudden reversal of all Trump’s policies is probably going to be disappointed.Analysts say he is not going to suddenly give China, Britain or the EU exactly what they want on trade.Typically in the past it has often been Democrats more than Republicans who have been sceptical about free trade.Expect change - but as UK prime minister Boris Johnson said, don’t expect Joe Biden to be a pushover.