Grexit, Grexident and Greferendum

Grexit, Grexident and now Greferendum – the debt crisis in Greece has thrown up plenty of portmanteaux, as linguistics professors call these often-tortuous combinations of words.

And with Greferendum becoming a reality this weekend, it now looks increasingly likely that the other portmanteaux will move from concept to execution. Greek Prime Minister Alexis Tsipras's Mr Smith Goes to Brussels act doesn't seem to have achieved as much as those who voted for him hoped; they might have been better off with a Frank Underwood from the "House of Cards"—less idealistic, but better at negotiating backroom deals.

Yannis Behrakis | Reuters

A European Union flag flutters before the temple of Parthenon at the Acropolis hill in Athens, Greece June 26, 2015.

History may prove Tsipras right, but it would be a pretty bittersweet victory for a leader who looks likely to soon be either out on his ear, or governing a country that has gone from developed to emerging or even frontier market in five years.

The Athens leadership's hopes—that the fear of Greece leaving the euro would help get it greater concessions—seem to have been dashed, with precious little hope remaining (at the time of writing) of a last-minute solution to the impasse between lenders and debtors.

Read MoreGreece: Uncertainty reigns after referendum gamble

Euro zone leaders may have underestimated investors' complacency about Grexit contagion, judging from the reaction of stock markets to the weekend's newsflow.

Yet Greece is far from the only jellyfish lurking in the water this summer for investors.

Greece's "toxic mix of private and public debt" and lack of "badly needed" structural reforms are particularly bad, as the Bank of International Settlements—the central banks' central bank that was one of the few bodies to predict the credit crisis—warned this weekend. But Greece isn't exactly the only country over-reliant on monetary policy and central banks getting it right, essentially.

Read MoreFather of Grexit: 'Disaster' for euro zone if Greece leaves

The addition over the weekend of the "Zhou put" – a reference to the People's Bank of China Governor Zhou Xiaochuan's actions to ease monetary policy – to the list of terms economics students of the future will be studying, shows how even the economy expected to overtake the U.S. as the world's biggest cannot rely on growth any more. The cut in policy rates and selected bank reserve requirements, was reminiscent of the era of former U.S. Federal Reserve Chairman Alan Greenspan.

Chinese equities, emerging markets, Iran's nuclear talks and let's not forget the continuing lack of resolution of the Ukrainian conflict, are all potentially big negatives for markets in the next few months.

This could be the year where the old stock market adage "sell in May and go away" is more accurate than ever.