Richard Pilley, an adviser at Milford Asset Management, pointed to data showing the performance of $100,000 invested in America's S&P500 since 1988.

If an investor missed the best five days in the market in that time, their investment would be worth $675,788 or 35% less than if they stayed invested the whole time.

If they missed the best 25 days, they would be left with just $404,781 now compared to $1.9 million if they had stayed in.

"Advisers should be encouraging clients to focus on their long-term goals rather than looking at short term market movements and other 'noise'," he said.

"This is easier said than done as it is very tempting to be distracted by short-term volatility. However, the adviser should have had a detailed discussion with their client to decide on a long-term strategic asset allocation based on the clients’ objectives, tolerance for risk and other factors such as income requirements.... These discussions should take place at regular intervals to ensure the clients’ objectives are on track to be achieved, and include an explanation of market movements and volatility so clients know what to expect."

He said it was important to get long-term strategic asset allocation right to ensure clients achieved their objectives as dictated by their financial position, preferences, estimated timescale and risk profile. 

"However, that’s not to say that shorter term market movements can simply be ignored. An active discretionary investment manager, for example, will overlay short-term tactical asset allocation decisions, anywhere between 0-36 months, on to the long-term strategic allocation in order to take account of prevailing market conditions and other factors.

"In addition to the tactical overlay to the overall allocations, the use of actively managed funds within a diversified portfolio is beneficial as they have various tools available to mitigate downside risk, such as derivatives which when used correctly can act like financial insurance policies, which are difficult for the private investor to access."

Pilley said clients should get some comfort from that, and other active management, because it meant they were not just at the mercy of markets.

"The majority of clients we speak to are relatively relaxed about market volatility and do not concern themselves with trying to time the market. They have lived through market cycles and are comfortable that, over the long term, they will achieve their objectives. They also trust their discretionary investment managers will make appropriate tactical decisions to mitigate downside risk and take opportunities on the upside.

"However, we do speak to some potential investors who are worried about entering the market. Sometimes, these individuals have been waiting on the sidelines for years because they fear that in the short-term values will fall - there are always excuses not to invest if you read enough news articles! -  and so unfortunately they have missed out on some good returns, over a period of years, while their money sits in the bank."

Pilley said even if clients did not bring it up, it was important for advisers to explain volatility.

Many would have forgotten what "normal" levels of volatility looked like, he said.

"We can all play our part, advisers, financial service firms and commentators.  For one, our explanations to clients include this and we try and help our investors understand markets. That said, most clients want to leave the worry to us. That’s the advantage of having an adviser."