European markets are getting crushed and nobody knows who'll win the Greek referendum

European markets are getting a kicking Monday morning, after Greek Prime Minister Alexis Tsipras' shock referendum announcement on Friday.

Analysts expected that we were heading into the final, last-chance stage of Greece's bailout negotiations, but instead, Tsipras opened the question up to the country.

He's been in charge of negotiating the deal, but says what's on the table isn't good enough - so he's campaigning against the agreement.

Greek markets, like the banks, are closed - it seems extremely unlikely that they'll open again before the referendum scheduled for Sunday June 5. The Athens Stock Exchange has been volatile enough in recent weeks, and the country's current status would almost certainly cause total mayhem.

Other European markets are getting smashed this morning. Here's how they look:

• Germany's DAX: -4.11%
• France's CAC 40: -4.22%
• Spain's Ibex: -4.52%
• The UK's FTSE 100: -2.26%
• Italy's FTSE MIB: -4.63%

Nobody knows which way the referendum will go. A yes vote would back the bailout deal, along with the austerity and painful economic reforms Greece's creditors are demanding. That's the option more likely to keep Greece in the euro.

On his own blog, Greek finance minister Yanis Varoufakis' own blog gave a "high probability" that the Greek people would accept the deal.

Not everyone is so sure. The Economist Intelligence Unit gave a 60% probability that voters would instead back the government and reject the bailout.

According to HSBC analysts, the early polling suggests Varoufakis is right:

The population may not know what they will be voting on but the opinion polls have inevitably already begun. Kappa research has published a poll conducted today for "To ima" newspaper. In response, 47.2% said they agreed with the deal proposed by the creditors, 33.0% said No, 18.4% were undecided and 0.8% didn't know or wouldn't answer.

The result might not matter - on Tuesday, the government's current bailout expires and as far as the Eurogroup (the bloc of eurozone finance ministers) is concerned, Greece can't just choose to extend it at a week later.

But everything is up in the air at the moment. Though the deadline may expire on Tuesday, it's hard to see Greece being slowly ejected from the euro just because its referendum was a week late.

Markets are feeling that uncertainty. It's not difficult to spot what happened to Spanish bond yields Monday morning:

The story is similar for Italy, and in Portugal 10-year yields spiked over 3%. But that's not much of a climb compared to the euro crisis.

Take a look at this longer-term view:

One of the last remaining cards in the Greek government's hand is the potential for contagion - that Greece's drama would spread beyond its borders, causing pain in financial markets across southern Europe. Between 2010 and 2012, during the euro crisis, fear of contagion persuaded sceptical European politicians to do everything necessary to keep Greece in the euro.

This time round, so far, it doesn't look like they have the same pressure to act.