The mood in markets is very positive, with emerging markets posting their best day since 2022. A ceasefire is a particularly large relief for small crude oil importing nations, particularly those ones that relied on Middle Eastern refineries.S&P 500 futures are up 2.6% and WTI crude oil is down $20 to $92.93 in one of the largest one-day losses ever.The fear at the moment is that the ceasefire won't hold. The FT is out with a report just now on a drone strike on Saudi Arabia's east-west pipeline to the Red Sea and that's boosted oil by $2. There's also Lebanon, which Pakistan and France said were in the ceasefire agreement but video shows Beirut being hit with dozens of bombs today.The US said yesterday that it would take some time for the ceasefire news to get to all of Iran's commanders but there is surely a limit to that.There is certainly some optimism in markets but it's fragile. The main thing is that Trump seems to be done with the war but it's not so easy to ensure the peace and his habit of brinksmanship will make negotiations thorny. Worse is that it's not clear what any side has agreed to as Iran's plan includes control of the Strait and reparations.For now, this is a big relief rally and that's the right reaction but it won't immediately end the intense focus on Middle East headlines. With a mood swing from Trump, this could all come tumbling down and leave the market in an even-worse place, with potential for strikes on energy and an endless blockade.This is reminiscent of the early TACO from Liberation Day when it wasn't clear where tariffs would land and it wasn't yet clear that the EU would entirely roll over and accept them. Ultimately, the good news held and markets marched much higher.In the AI space, it looks like Anthropic has a new blockbuster model with others surely to follow. That should put the AI trade on firmer fundamentals and keep the momentum going. This article was written by Adam Button at investinglive.com.