If there is one thing you can count on, it is to be prepared for a long day/night in the US. Pollsters haven't had a good track record in general when calling the outcome but they are still the best guide you can go with in approaching these things.
But for a bit of context, the onus is on Republicans to turn the tide (five seats to take the House and just one to take the Senate). So, what are the expectations?
The predictions are showing that Republicans are almost certainly going to win a majority in the House but the Senate contest may be a much closer affair. There are plenty of little nuances with regards to each state and the way that the ballots will be counted, so don't expect any straightforward results just based on early counting. The tide can quickly turn against the Democrats if election day votes are counted later and the same for the Republicans in states where mail-in ballots are counted later instead.
To put things short, it is best to think of this as election week instead of it being election day. If the results in some states are more tightly contested, especially for the House, then it will take some time to sort out who will come out on top.
As for the Senate, it could take even longer to settle the score in the event that Georgia heads into another run-off election - which will then take place on 6 December. As such, it could take up to a month to really get an idea of how Congress will shape up.
What is the impact of all this on markets? In a time when the world is largely focused on inflation, recession risks and a global energy crisis, the control of Congress isn't going to matter all too much in my view. I mean, even if we do see a divide in power, it is not to say that things aren't already gridlocked in US politics at the moment.
Regardless of whoever wins, it doesn't seem like there will be potential to push through any meaningful legislation. I mean if Republicans take control of both the House and Senate, maybe there's a chance but otherwise, there shouldn't be any major or long-term repercussions to the election result.
In case you missed it, Adam has put up a couple of good posts on this matter over the past week: