Dollar-cost averaging simply involves investing the same amount of money into shares or other securities at regular intervals – whether prices are up or down.

Investors practising dollar-cost averaging automatically buy more, say, shares when prices are lower and fewer when prices are higher. In short, purchasing costs are averaged over the total period that an investor keeps on investing, thus the name dollar-cost averaging.

Yet the core attribute of dollar-cost averaging is not so much the price paid for securities; it is the adherence to a disciplined, non-emotive approach to investing that is not swayed by prevailing market sentiment.

Dollar-cost averaging can assist investors to focus on their long-term goals with an appropriately diversified portfolio while avoiding emotionally-driven decisions to buy or sell – in other words, trying to time the market. As Smart Investing repeatedly emphasises, investors would rarely succeed consistently at market-timing.  The Forbes article, Five tips to make you a better investor in 2017, reasons that dollar cost averaging strategy may be well suited to millennial investors given their long investment horizons and their perhaps relative inexperience in investment markets. As a financial planner quoted in the piece comments: "The logic here is, if you're in your late twenties or early thirties, the fluctuations of the market on one given day are unlikely to have serious consequences to the retirement money you'll need to withdraw 30 years from now." Novice investors were "too easily" influenced by market movements.

And given their long investment horizons, millennial investors are well placed to benefit from the rewards of compounding as investment returns are earned on past investment returns as well as on the original capital. (See Save early, save often, Smart Investing, January 29.)

The use of dollar-cost averaging does not necessarily mean, of course that investments will succeed; nor does it protect investors from falling share prices.

Australian super fund members who have compulsory and/or voluntary contributions regularly paid into their super balanced accounts are practising a form of dollar-cost averaging. The higher the regular contributions, the greater the potential effectiveness of dollar-cost averaging over the long term.

The vast majority of investors practising dollar-cost averaging would invest regular amounts from their monthly salaries. Yet a related issue concerning dollar-cost averaging can occur when an individual has a large amount of money to invest, perhaps from an inheritance, a bonus from work or some other windfall.

Several years ago, a Vanguard research paper found that, given certain assumptions, investing a big lump sum all at once had a better chance of producing higher long-term returns than drip-feeding the money into the market using dollar-cost averaging. This finding was based on historic long-term returns from share and bond in Australia, US and UK. As the paper emphasises, investment of a lump sum gains exposure to the markets as soon as possible.

Another consideration is that dollar-cost averaging may address concerns of a risk-averse investor about investing a big sum into the market immediately before a possible sharp fall in prices. It is a way for such an investor to ease their way into the markets.
For most investors without a huge windfall to invest, a critical role of dollar-cost averaging is to help keep us focused on the long-term in a disciplined, non-emotional way. It is one of investment's emotional circuit breakers.

Robin Bowerman
​Head of Market Strategy and Communications at Vanguard.
19 March 2017
www.vanguardinvestments.com.au