Skip to main content

Why Cost Averaging Really Does Work

You aren't smarter than the market. It really is that simple.

There are a number of places on the internet and in the media where people have questioned the value of "cost averaging". Cost averaging is investing in regular amounts over time, rather than in one lump sum all at once. It has been standard investment advice, but now some critics are arguing that, since the market in the long run tends to go up, the earlier you invest the better. Cost averaging will reduce your return in the long run.

They are, of course right. On average, you will get a lower return. But cost-averaging is not done to maximize returns. Its used to minimize risk. It is a strategy to make sure you get an "average" return instead of hitting just one peak or one valley.

Think about it this way. Suppose someone offered to flip a coin and pay you $51,000 if it was heads, but you would have to pay them $50,000 if it comes up tails. Would you take that bet? On average, you would come out ahead. But only a gambler makes that kind of bet unless you can afford to lose the $50,000. On the other hand, if they offered to flip a coin 1000 times with the same odds, you might be tempted. The odds are still in your favor and you are unlikely to lose every time and cost you $50,000. Of course you are also unlikely to win every time and win $51,000 either. Instead you have a good chance of coming out ahead somewhere between those two exremes.

The market works the same way. If you want to maximize your return you, flip the coin once. If you want to minimize risk you spread your flips out. Most of us are trying to be investors, not gamblers. We want to make a reasonable return while preserving what we have. So lets look how this works in practice.

If you have $5000 to invest in your IRA and invest it on the first of the year you will do better, in the average year, than if you put $100 into your IRA over the course of the year. The problem is that not all years are average. More importantly, not all starting points are average. Some years the value of stocks will be higher to start the year than the average over the course of the year, other times it will be lower than average. In fact, in the current market, that is true from week to week as you can see in the example below.

This year I decided to basically add $100 each week to my IRA. The details are a bit more complicated than that, but I am simplifying here. So what do those investments look like:

Date Shares Security $Invested

1/6/2009 5.893 Vanguard Balanced Index Fund Investor Shares $100 
1/13/2009 6.127 Vanguard Balanced Index Fund Investor Shares $100 
1/20/2009 6.427 Vanguard Balanced Index Fund Investor Shares $100 
1/27/2009 6.250 Vanguard Balanced Index Fund Investor Shares $100 
2/3/2009 6.301 Vanguard Balanced Index Fund Investor Shares $100 
2/10/2009 6.329 Vanguard Balanced Index Fund Investor Shares $100 
2/17/2009 6.489 Vanguard Balanced Index Fund Investor Shares $100 
2/24/2009 6.588 Vanguard Balanced Index Fund Investor Shares $100 
3/3/2009 7.018 Vanguard Balanced Index Fund Investor Shares $100 
3/10/2009 6.887 Vanguard Balanced Index Fund Investor Shares $100 
3/17/2009 6.562 Vanguard Balanced Index Fund Investor Shares $100 
3/24/2009 6.394 Vanguard Balanced Index Fund Investor Shares $100 
3/31/2009 6.460 Vanguard Balanced Index Fund Investor Shares $100 

You will notice that the first shares I bought were also the most expensive. Had I invested to my IRA limit to start the year, I would likely end the year with many fewer shares than I will by my strategy of cost averaging. In January and February, I came out ahead with lower prices later in the month. In March, I would have been better off to purchase on March 3rd, when prices hit bottom for the year so far.

That is true, even if stock prices eventually recover to the level they were in January. The only way I will come out behind is if the average price I pay over the course of the year is higher than it would have been in January. Otherwise I will end the year with more shares of stock, regardless of their price at the end of the year. If 20 years from now, I sell the shares from these transactions, I am going to get 20% more money for the shares I purchased on March 3rd than I will for the shares I purchased on January 6th. That is a pretty significant difference.

I am looking only at share prices here. But there is another factor to consider in evaluating the overall return. That is any dividend payments I receive. Because my IRA is not getting dividends on shares I don't yet own.  Of course, the dividends in the future will also be higher since I own more stock. 

Which just clarifies when cost averaging makes sense. If you are buying investments where the primary return is from dividends and/or interest, you probably don't need a risk limiting strategy like cash averaging. But if you are buying securities whose price is volatile, cost averaging will reduce your risk and sometimes save you from paying a premium price that you will never recover.

Comments

Popular posts from this blog

Who is to blame for this mess?

There seems to be a lot of discussion to who is to blame for the financial crisis. But an awful lot of the media coverage is highly misleading. Here is synopis: 1) The meltdown in the financial market had little to do with people getting mortgages they couldn't afford. The collapse of the mortgage backed CDO's was caused by the collapse in the value of the houses which provided the collateral. It turned the mortgages behind the "collateralized debt obligations" (CDO's) into mostly un-collateralized debts. The result was that they went from AAA rated bonds to junk. 2)So what caused the housing bubble and collapse? Many people blame the fed, but don't have the story right. The fed did play a role. By keeping interest rates on Treasury Bonds low, they provided a market for alternative bonds that would pay a greater return. But the major cause of the housing bubble was the creativity of the investment banks. These are not the retail banks that make home mortgages ...

Self-Directed Real Estate IRA's the New Scam?

You aren't smarter than the market. It really is that simple. You know the marketing folks have been out talking when the New York Times does a fluff story on some new way to make more money with your investments. So watch out for the new scam promoted by the same media advisers who told you a few years ago to buy the most expensive house a lender would finance. Paul Sullivan story is about people'e successful investment of their retirement money in real estate using a self-directed IRA. He provides us with several "success stories".  Of course they are all recent converters to this idea and, not surprising, all but one of the people whose story Sullivan tells are also in real estate sales. The problem isn't really Paul Sullivan. Its that there is no one who makes money by digging out the horror stories from people who invested their retirement funds in real estate at the height of the housing bubble. There aren't any public relations firms devoted to de...

The Stock Market hasn't gone up, the Value of the Dollar has Just Gone Down.

You aren't smarter than the market. It really is that simple. The New York Times had an article about the stock market's recent gains. The story noted that while the market had gone up 11% since the election, the dollar had dropped 10% against a basket of foreign currencies during that same period. They described this as "almost a mirror image." Unfortunately it is exactly a mirror image for people who hold those foreign currencies. Lets say they paid a $100 for a share of stock the day of the election and they exchanged 100 units of their own currency for that $100. Now if they sell that stock they will get $111 dollars, but when they exchange that $111 dollars, they will get back 100 units of their own currency. They have earned nothing, in their own local currency's terms the price hasn't changed. In a world investment market, the price of stock is set by what people around the world are willing to pay for it. Most people are still paying the same pr...