LONDON (MarketWatch) — The hedge funds will have prepped their positions. The investment banks will have ordered in pizza and extra coffee ready for a long night of dealing. Exit polls will have been commissioned, and currency traders will be ready to buy or sell sterling GBPEUR, +0.02% as soon as they start getting a clear idea of whether Britain has voted to stay in or get out of the European Union on June 23.

But hold on. In fact, it is not just the risk of Brexit that the markets need to be worrying about. In truth, the real drama is going to come over a long and difficult weekend, leading up to potentially wild day in European assets on Monday, June 27.

Why? Over that weekend, Spanish voters will go back to the polls in another attempt to settle on a government, which may well see the far-left Podemos group make big gains. Greece will be struggling to find the money to pay back its latest debts. And if the strikes in France escalate, the country may be close to running out of its strategic fuel reserves — and approaching a total meltdown.

Brexit, Spexit, Grexit, and Frexit could all collide. The result? A car crash for the European markets.

Brexit remains the most pressing worry for investors, and rightly so. With three weeks until the vote, the polls remain very close. The latest sample for the Daily Telegraph showed a five-point lead for “Remain,” and most have showed the two camps within five to 10 points of each other.

But who knows what is going on? The U.K. hasn’t had a referendum like this for a generation. No one knows what questions to ask, what demographics to target and which side will be better at getting its people to the polling booths on the day. Either side could win comfortably.

Here is the interesting point, however. It may take until the weekend to work out what has happened. The TV networks have decided against an extensive exit poll, on the grounds that they don’t know how to make it accurate. The hedge funds are reported to be spending a lot of money on private exit polls, and the currency markets will tell us what those results look like.

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But who is to say they are reliable? In fact, if it is close, we may have to wait until the votes from some of the far-flung regions of Scotland are counted, which means a final result may take a day or two. And that is only the start of the fun. Will Prime Minister David Cameron stay or go? Your guess is as good as mine. He probably won’t know himself until at least Sunday the 26th.

At the same time that is happening, Spain will be going to the polls. Last year’s election resulted in a stalemate, with the vote split between four parties who could only agree on one thing — that they all hated each other.

This time around, the result is not likely to be radically different, except in one important respect. The polls suggest that the anti-austerity Podemos party may well make the most significant gains — one shows it with 24% support, which would make it the second largest party, and its alliance with the United Left may mean it gets many more seats than that in Parliament.

Much like Syriza in Greece, Podemos rejects the spending cuts imposed by the eurozone, and demands a complete change of direction on the economy. If it gets anywhere close to power, the markets will rightly feel very nervous. True, Syriza backed down in its confrontation with the EU and the IMF. But it was a hair-raising ride, and there is no guarantee Podemos will do the same.

In truth, Spexit will be back on the agenda.

It doesn’t end there. Like a bad cold, Greece is the problem that never goes away. In July, the country is due to repay 2.3 billion euros to the European Central Bank. A deal has supposedly been agreed to roll over its never-ending bailout.

Think nothing can go wrong with that? Over the last six years, the country has proved remarkably accident prone. It hasn’t managed to get through many summers without some sort of crisis. It would take a lot of confidence to bet that this one will be any different. If it can’t find the money, then Grexit will be looming once more.

And here is a wild card to add into the mix. France.

France is grinding to a halt as trade unions stage strikes over a relatively modest tweak to the labor laws. Refineries have been shut down and fuel is now in short supply — close on half the gas stations have already closed. Nuclear power satiations are on strike, and so are the railways. The country has already started dipping into its strategic fuel reserves, and in mid-May said it had 115 days of supplies stockpiled. Add in some panic buying by motorists, and by the end of June those could be running perilously low.

France has been in economic decline for years now, with dangerously high unemployment, and yet somehow always struggles on. But if the government of President Francois Hollande collapsed amid a wave of protests, the anti-euro Marine Le Pen would be waiting to seize power. The chances of that happening are not high, for sure — but it is also not impossible. If it did, Frexit would be on the horizon.

None of that may happen.

Britain may decide to stay in the EU by a comfortable margin. Spain may decide it might as well re-elect Prime Minister Mariano Rajoy rather than prolong the uncertainty. Every crisis may be easily fixed.