Say you've picked your assets. You still face a second decision that quietly drives most of your results: how much of each to hold. That's the weighting scheme, and there are three big families.
Capitalization weighting holds each asset in proportion to its market size. This is how the S&P 500 works: a company worth 7% of the index's total value gets 7% of your money. It's cheap to run and self-adjusting, but it concentrates you in whatever has already gone up — by the mid-2020s, a handful of tech giants made up roughly a third of the index.
Equal weighting splits money evenly: ten assets, 10% each. It's simple and avoids concentration, but it treats a jumpy small-cap and a placid utility as interchangeable, and it needs regular rebalancing — selling recent winners to top up recent losers.
Risk weighting, the family that includes risk parity, asks a different question: not how many dollars go into each asset, but how much risk each asset contributes. Risk, it argues, is what actually hurts.
The classic balanced portfolio holds 60% stocks and 40% bonds. It sounds diversified. Measured in risk, it barely is.
Here's why. Stocks are far more volatile than high-quality bonds — historically something like three times as volatile. Volatility, recall, measures how much prices swing. When one holding swings three times harder than the other and also gets more of your money, it dominates the portfolio's behavior. Run the math on a 60/40 mix with stocks at 15% volatility and bonds at 5%, and stocks account for over 90% of the portfolio's total risk.
The consequence shows up in every crisis: when stocks fall 30%, a 60/40 portfolio falls nearly as hard in risk terms, because it was never really balanced — it was a stock portfolio with a bond garnish. Risk parity begins from this critique. If diversification is the goal, it argues, balance the risk, not the dollars.
Let's build a tiny risk parity portfolio. Two assets: stocks running at 15% annualized volatility, bonds at 5%. Goal: each contributes equal risk.
The simplest version weights each asset by the inverse of its volatility — the less volatile an asset, the more of it you hold. Bonds are one-third as volatile as stocks, so they get three times the weight. Solve it out and you land at 25% stocks, 75% bonds. Check the risk contributions: 25% times 15 equals 3.75 units of risk from stocks; 75% times 5 equals 3.75 from bonds. Balanced.
Now the catch. Assuming the two move independently, this portfolio's overall volatility works out to only about 5% — very tame, and its expected return is correspondingly modest, since three-quarters of it sits in the lower-returning asset. You've bought balance at the price of punch. In a fuller version, correlation matters too: correlation measures whether assets move together, and assets that zig when others zag earn extra weight because they hedge the rest. But the core trade-off survives every refinement: unlevered risk parity is smooth and modest.
Risk parity funds answer that question with leverage — investing borrowed money on top of your own. If the balanced 25/75 mix runs at 5% volatility and you want the roughly 10% volatility of a conventional stock-heavy portfolio, you lever the whole thing about two times: for every dollar of capital, hold two dollars of the balanced mix, financed by borrowing.
The pitch: a levered balanced portfolio and an unlevered concentrated one can target the same total risk, but the levered one spreads that risk across assets, which — if the assets take turns misbehaving — has historically meant shallower worst stretches. Large risk parity funds launched since the 1990s made this argument famous.
Leverage, though, imports its own risks. Borrowing costs float with interest rates, so the strategy's economics worsen when rates rise. Levered positions can face forced selling at the worst moments: when volatility spikes, a fund targeting constant risk must shrink, dumping assets into falling markets. And leverage means you can lose more than the unlevered math suggests. Risk parity doesn't eliminate risk. It rearranges it — from concentration risk into leverage and correlation risk.
Every weighting scheme embeds an assumption, and risk parity's is that bonds cushion stocks — that when equities fall, high-quality bonds usually rise or hold steady. For most of the 1980s through 2021, that assumption paid. Then 2022 arrived.
Inflation surged, and central banks raised interest rates at the fastest pace in four decades. Rising rates push bond prices down — that's mechanical, since old bonds paying low rates become less attractive. So bonds fell hard: a broad U.S. bond index lost about 13%, its worst year on record. Stocks fell too, with the S&P 500 down about 18%. The cushion and the thing it was cushioning hit the floor together.
Risk parity had a bad year — prominent funds posted losses in the range of 20% or worse, in some cases deeper than a plain 60/40 mix, because leverage amplified a bond bet that failed. The honest reading isn't that risk parity is broken; over longer stretches its record includes genuinely smoother rides. The honest reading is that its diversification relies on a negative stock-bond correlation that is a historical regime, not a law. When inflation drives the bus, stocks and bonds can crash together. They did it in the 1970s too. Backtests dominated by one regime flatter any strategy tuned to that regime.
You don't need borrowed money or a fund launch to use the core insight. Think in risk contributions, not dollar allocations. It changes decisions immediately.
When you look at any portfolio — yours, or one shared by another investor — ask what fraction of the risk each position contributes, not what fraction of the money. A 10% position in a stock that swings 60% a year is a bigger bet than a 25% position in a diversified bond fund. Plenty of portfolios that look diversified by dollars are, in risk terms, one large bet wearing a costume.
Testing weighting schemes against history is worth doing, with two warnings. First, the scheme that won the past few decades won partly because of the regime it lived in — a forty-year bond bull market made anything bond-heavy look brilliant. Second, weighting schemes are the easiest thing in investing to overfit: with enough tinkering, some weighting always looks optimal in hindsight. Prefer schemes with a reason to work — a story about risk you'd believe even without the backtest — and assume the measured edge will be smaller going forward. It usually is.
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