The old adage of “sell in May and go away” has some credence, according to a study released by Toronto-based BMO Private Bank on Thursday, but advisors still need to stay focused all year long.

To test the validity of the well-known strategy, BMO tracked US$1,000 invested in the Dow Jones Industrial Average in November through to April between 1900 and 2012. Another US$1,000 was invested in the Dow in May through to October over the same time period. When not invested in the Dow, the money was switched to non-interest bearing cash.

The study found that money invested solely between the months of November and April earned an annualized price-only return of 4.3%, whereas in May to October the return was a mere gain of 0.7%. However, while this may seem to prove the point, results show that money invested throughout the year earned a return of 4.7%.

As such, even though the summer is a slower time for investing, for better returns advisors need to pay attention to clients and their investments year-round.

“We’re monitoring the market and its internals on a daily basis,” says Jack Ablin, chief investment officer, BMO Private Bank in Chicago. “And we are talking to investors and trying to get a sense of their level of confidence or conviction in the market.”