Long-term investors would do well to keep an eye on the upcoming European Parliament elections in all of the 28 member states that will take place from May 22 through May 25.

On the evening of May 25, we should know for whom and for which parties the Europeans have voted. However, we could have to wait until July 14 through 17 when the newly elected EU parliament will finally vote on the European Council's nomination of the Commission president, which should have been agreed upon at its plenary summit on June 26 and 27.

That waiting period by itself could become a serious source of uncertainty in the coming months. I'm not saying it "will" because all will depend on the results of the votes that will be counted on Sunday.

Don't overlook the fact that outgoing European Council President Herman Van Rompuy publicly reiterated his personal reservations about the five (yes, you read five!) pan-European proposed candidates for the EU presidency, stressing the next EU Commission president "needs a large majority in the EU Council too."

Van Rompuy stated: "There must be 1) a simple majority in Parliament, which is 376 votes, and there must be 2) a large majority in the European Council of the 28 heads of states."

He left no doubt whatsoever the next EU Commission president would need the backing of both institutions and that he will respect the Treaty and try to prevent a "clash" (in clear English = crisis) of the institutions. In all honesty, I wish him good luck, because, in case trouble arises he will need it.

Very few people in the world understand the complexity of how the European Union applies its own rules on democracy, but that's the way it is. Maybe, this explains why an astoundingly vast majority of EU citizens isn't interested in the European elections at all.

This disproportionate lack of interest could even worsen after the elections, but let's hope it doesn't come to that because that by itself wouldn't bode well for the future of the European Union and especially its consolidation process into a real coherent and stable political block. No, the EU woes aren't over yet.

Besides all that, for many investors it's difficult to overlook the events that are taking place in the important emerging economy of Thailand. Thai Army General Prayuth Chan-ocha has declared nationwide martial law, which he says is not a coup d'etat.

However, the government's security unit, the Center for the Administration of Peace and Order, has been dissolved and replaced by a military-staffed organization.

Of course it's completely impossible to know how the political situation in Thailand could develop from here, but I think investors would do well to take notice all this occurs at the same time we see a weakening Thai baht, which is down approximately 9.4 percent year-over-year against the dollar, and the Stock Exchange of Thailand, which is down 12.36 percent year-over-year.

Looking at it in the context of what is going on in various places in the world, I can't resist extrapolating if events in Thailand should develop into a new crisis, which would prove without any doubt to be disruptive for both the Thai baht and local equities. It could also ignite broader risk aversion, not at least because of the many rising geopolitical uncertainties, but also market values in many locations that, I believe, are sending out worrying price signals at present, such as currency values against the dollar, commodity values, etc.

This could become, once again, some kind of a lynchpin for bringing back that old well-known theme: "Sell in May and go away," as the month of May develops further, and that could turn out, in my opinion at least, not such a bad idea at all.

I'm not saying the whole thing is going to implode now, and although I might have become too cautious too early, I still am convinced we are prone for an abrupt sell-off that could easily happen earlier rather than later. Long-term investors should be prepared for when the swift sell-off really starts it won't be a straight path down and there will come a nice rebound (wave) that, when it comes, could prove equally swift.

Finally, today's persistent complacency and optimism in many places, usually is a hallmark of aged rallies and market tops as history teaches us. I don't believe it will different this time.

As we see, at least until now in crude oil futures we have not only record net long positions among large speculators (the optimists), but also record net short positions among "commercials" (the realists), who, as we know from the past, are most of the time on the right side of the markets they trade. You don't have to be a rocket scientist to understand that long markets can't indefinitely stand such a high level of optimism among "big" oil investors/speculators and realism among the established commercial oil buyers.

By the way, oil futures remain, for the time being at least, in backwardation, which means the price for future delivery is lower than the spot price or lower than a nearer future delivery.

For example, New York West Texas intermediate crude oil for June delivery closed Monday at $102.61, while December 2014 closed at $97.26, June 2015 closed at $92.78 and December 2015 closed at $89.78.

While it's not difficult to see where the oil price should be headed under normal circumstances, that's certainly not an inflationary signal.