Polling in Greece is banned in the two weeks leading up to an election, so we have very little information as to what the likely outcome of the 17 June vote will be. It will definitely be New Democracy, the conservative party, and Syriza, the radical left, in the top two places; and the margin is unlkely to be more than 3 per cent either way. But beyond that, everything is very up in the air.

Business Insider's Joe Weisenthal, however, points out [2] that the Greek stock market has surged today:

[3]

He says [2]:

According to Greek stock market participants, there are "secret polls" that show the pro-bailout New Democracy party is leading and likely to win this Sunday's election. Technically, polling is banned for the two weeks prior to the election, but the parties and so forth are still keeping tabs on the mood of the electorate, and these polls can get out. 

Furthermore, Greek betting sites have shown also a spike in bets placed on New Democracy, and this too is seen as evidence of a shift. So traders like the stability of the pro-bailout, conservative New Democracy party over the chaos of the left-wing Syriza party, and thus at least right now are speculating that the status quo wll remain.

All of this is to be taken with the biggest grain of salt possible, of course. It's an inference from an inference – no one is on the record as having actually seen these polls and it's all too easy for a rumour like this to become self-sustaining. But the market is hungry for information from Greece, and any will do.