While there appears to be some validity to this seasonal pattern, many investors and analysts would not be swayed by such statistics.
However, I wouldn't be at all surprised if "selling in May" works this year, at least to some degree.
For a start, global economic activity has really stalled in recent weeks. In the US we've seen the weakest jobs report in 18 months and economic growth has slowed to just 0.2 per cent. Annual corporate profit growth is the weakest since 2009, despite markets hitting new highs.
Economic growth in the UK has also missed expectations and European data remains lacklustre, despite aggressive money printing in the region.
Chinese industrial production is at its lowest levels since 2008, with this weakness reflected in the panicked monetary easing we have seen recently from China's central bank.
Numerous geopolitical risks are still lingering in the background, despite a bit of calm in recent times.
The situation with Russia and Ukraine remains unresolved, Middle East tensions are still running high, and Greece's insolvency has merely been delayed rather than dealt with.
Despite all of this, markets have continued to rise and many are hovering close to record highs. Shares in all regions are trading above their long-term averages, making value much more difficult to find.
Having said that, low interest rates are distorting traditional valuation measures and investors are much more focused on relative valuations.
In other words, shares could remain (or get more) expensive for as long as interest rates stay at close to zero (or negative) in many places.
I certainly don't have a doom-and-gloom view of the world, but I do think investors have become a little too complacent of late.
Apply a bit of caution over the coming months and consider taking profits in higher-risk positions. For newer investors, being patient could pay off. If we do see some weakness creep in, this could represent an attractive buying opportunity.
New Zealand remains in good shape, but we can't ignore what is happening with our two biggest trading partners (Australia and China) or the fact that moves in bigger financial markets overseas will still be felt on our shores.
Liquidity problem urgent, says Greece
Greece may have only a couple of weeks left before it faces problems meeting its financial commitments, the country's finance minister conceded yesterday as talks with European creditors dragged on without agreement.
After a meeting with his peers in the eurozone, Yanis Varoufakis said Greece was being strangled by a liquidity problem that could become "binding" in a couple of weeks.
"The liquidity issue is an incredibly urgent issue," he said. "Let's not beat about the bush and pretend otherwise ... It seems to me that from the perspective of the timeframe that we are facing, we're talking about the next couple of weeks."
Greece is facing an acute cash crunch that many in financial markets think could see the country default on its debts and possibly leave the euro currency.
Greece and its creditors have been trying to agree on reforms and budget measures to get a bailout loan - worth 7.2 billion ($10.9 billion) - that will help it pay upcoming debts as well as meet its day-to-day obligations on things such as wages.
Yesterday, the country authorised a debt repayment worth 757 million to the International Monetary Fund.
The eurozone's top official, Jeroen Dijsselbloem, said progress was made at the meeting in Brussels yesterday but "more time and effort" was needed to reach a deal.
- AP
Mark Lister is head of private wealth research at Craigs Investment Partners. His disclosure statement is available free of charge under his profile on www.craigsip.com. This column is general in nature and should not be regarded as specific investment advice.