It is a bit of a tricky one as one can argue that investors were feeling more optimistic about the US-Iran conflict. But at the same time, I don't want to say it but month-end and quarter-end shenanigans might also be a factor in exacerbating the moves from overnight trading.The S&P 500 clocked in 2.9% gains yesterday, which was the biggest jump since May last year. Meanwhile, the Nasdaq posted 3.8% gains and that was the best daily move higher since May last year as well.After having been beaten down quite badly since last week amid a break of key technical levels, was the latest bounce yesterday a game changer? It depends.If there's anything the Covid pandemic taught us is that sentiment can be bad and yet, the stock market can rally. That was the case as equities bottomed out in March 2020 before picking up in April 2020 and I think we can all agree that we never looked back after that.This time around, it seems that there is a converging view that US president Trump is going to put a stop to the war sooner rather than later. We've hit his pain threshold in markets surely and even if he didn't exactly get the outcome he wanted from Iran, he will still try to frame this all as a "win" before taking a step back.At this stage, I think he knows very well that he can't really and truly win the war without reopening the Strait of Hormuz. And the longer this status quo carries on, the worse it will be for markets.The big question is what will happen to passage along the strait once the US pulls back? Does Iran continue to hold some restrictions to maintain leverage? Or are we going to see normality slowly resume? That remains the biggest caveat.Going back to US stocks, the bounce yesterday was encouraging and could be a key signal of a major sentiment shift. However, it still lacks a meaningful breakthrough on the charts.While it does mark a major turn from the downside momentum from the middle of March, the neckline break around the 6,525-50 region is still somewhat holding. And that will be the key area in determining whether or not the latest bounce has more going for it. That before a potential test up against the 200-day moving average (blue line) just above 6,600.Dip buyers might be starting to feel a bit more bold. But without a key break on the charts in the levels outlined above, the downside momentum is still the one very much favoured. That especially if the US-Iran conflict continues to drag on for another week or two before any real progress in ending.Looking to the seasonal factor, April tends to be quite a good month for US stocks but for some hiccup in recent years.It is the third best month for the S&P 500 index over the past two decades. But amid a time period where headline risks and geopolitical tensions are acting as the biggest drivers in trading sentiment, any seasonal push and pull will have to take a backseat. So, just keep that in mind.For me, I'd be eyeing the technicals very closely now in trying to get a better sense of the bounce from yesterday. That would be the best tell of market sentiment amid the mix of headlines that we will continue to see over the next few days/weeks.But even if it would seem that US stocks might look to turn a corner, just be wary that headline risks remain the biggest threat to derail any recovery. That and the fact that nothing changes for markets until something changes on the Strait of Hormuz. This article was written by Justin Low at investinglive.com.