Asset Allocation for Beginners: How to Split Your Money

New investors often focus on the wrong question, which is "Which fund should I buy?" The much more important question is how to split your money between different asset classes in the first place.

What is asset allocation?

Your asset allocation is your percentage mix of stocks, bonds, and cash. Stocks are the workhorse of a diversified portfolio, with the S&P 500 returning roughly 10% per year on average over the long run, though with substantial swings along the way. Bonds offer lower expected returns but far steadier behavior, and they often hold their value when stocks fall. Cash is the safest of the three, but after inflation, cash typically loses purchasing power. Mixing bonds and cash into a stock portfolio makes its returns far more reliable, at the cost of some long-run growth.

Why allocation matters most

Research has long found that the large majority of the difference in returns between portfolios comes from their asset allocation, not from which particular funds were picked. The classic studies here are by Brinson, Hood, and Beebower, whose analysis of large pension funds found that asset allocation explained most of the variation in portfolio returns over time, a result that reshaped how professionals think about the decision. A 90/10 split between stocks and bonds will behave very differently from a 50/50 split, regardless of which specific stocks and bonds are inside each. Two investors with similar timelines but different tolerances for swings should land on different allocations, and that decision will shape their results more than any fund choice.

What determines your allocation?

The single biggest factor should be your timeline. Stocks are the best performers over long stretches, but because they can drop hard in the short term, money you plan to spend within a few years belongs in bonds and cash instead. The second factor is your personal tolerance for risk.

Everyone's risk profile is different, based on their financial situation and what the money is for. A steadier, lower-yielding mix is safer but grows less. For most people, the right mix balances their timeline against how well they sleep during a downturn.

Some general guidelines by life stage:

	Early career (decades from retirement)	Middle age (within ~15 years)	Retiring soon
Stocks	80-90%	~70%	50-60%
Bonds	10-20%	~30%	40-50%

Another common rule of thumb is to subtract your age from 110, and hold that percentage in stocks. And if you don't want to manage any of this yourself, a target-date fund holds a diversified mix and automatically shifts more conservative as your chosen retirement date approaches.

Rebalancing keeps it on track

Once you have an allocation, remember that different asset classes grow at different rates, so your actual percentages slowly drift away from the target. Rebalancing means selling a bit of what has grown and buying what has lagged, restoring your intended mix and your intended risk level.

Once a year is plenty. If you are unsure what to trade, our portfolio rebalancer will tell you which positions to buy and sell to get back to your target. A target-date fund does this for you automatically. Trying to time the market is a dangerous game, and a well-thought-out allocation with periodic rebalancing is the much safer strategy.

The next time you sit down to think about investing, skip the question of which particular fund to buy for a moment. Decide first how you want to split your money between stocks, bonds, and cash based on your timeline and risk tolerance. That one decision, plus occasional rebalancing, does most of the work of keeping you on track.

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This article is for general educational purposes only and does not constitute personal financial, investment, tax, or legal advice. Consult a qualified financial professional before making major financial decisions. See our Disclaimer.