Dollar cost averaging in volatile equity markets

Does dollar cost averaging really work better in a volatile equity market?

Say that your equity market outlook assumes that one of two scenarios is true.  Either:

  1. You expect equity markets to be volatile over the next 10 years or,
  2. You are convinced that neither you nor anyone else knows what equity markets are going to do over the next 10 years!

but you still expect equities to outperform other asset classes over this term.

In this kind of environment a program of drip-feeding funds into the market makes sense as most research seems to suggest that market timers usually do worse than a more unemotional dollar cost averaging process

What is dollar cost averaging?

Dollar cost averaging refers to the process of investing the same amount to some regular timescale. When the price of the equities is low you will acquire more, and when high you will acquire less.

It may seem obvious, but is still worth stating, that dollar cost averaging essentially delays investing, which means that broadly as prices tend to rise over time this may reduce your returns…

Dollar cost averaging however itself has two problems aside from the implied delay element:

  1. There are transaction costs
  2. Can it be automated?

Transaction costs of dollar cost averaging

Ostensibly the transaction costs do not seem that high. You can download a very simple Excel model where you can put your own portofolio figures in here: Dollar cost averaging share purchases transaction costs.  

On the basis of $150k portofolio spread out over 10 sectors asset allocation sectors, with 10 trades per sector (100 trades in all), at $32 per trade (eTrade’s costs in Australia to private investors) you are looking at a transaction cost of around 2.13% on the whole portfolio using a dollar cost averaging strategy in establishing your portfolio:

Total sector holding 15000 Total portfolio size 150000
Total brokerage cost per sector 320 Total brokerage cost for portfolio 3200
Percentage return reduction for sector in brokerage 2.13% Percentage return reduction for portfolio in brokerage 2.13%

Can you fully automate dollar cost averaging?

In an ideal world many time-poor private investors would prefer to set up a plan in advance e.g. ‘complete my dollar cost averaging plan over the next 2 years’, for example.  

This raises the question of whether share purchase orders set ‘at market’  or ‘at best’ can be poorly priced, whether deliberately or accidentally by the broker?

The short answer is the jury is out …. there didn’t appear to be any easily identifiable research and presumably it differs on a broker by broker basis.

However a common-sense approach might suggest that low liquidity shares with bigger bid/ask spreads might be more at risk of mispricing than broadly traded shares or ETFs.   

Know better? Comment below.

Posted under investment strategies, market timing

This post was written by mike on July 21, 2009

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