What it means
Under equal weighting the arithmetic is simple: divide the money by the number of holdings and buy that amount of each. A $1,000,000 portfolio spread equally across twenty shares holds $50,000 of each, whether the company behind it is worth $2,000,000,000 or $2,000,000,000,000.
The contrast with market-capitalisation weighting is the whole point. In a cap-weighted index the largest handful of companies can account for a third or more of the total, so the index return is really their return; equal weighting deliberately removes that concentration.
The practical effect is a tilt towards smaller companies within whatever universe you started with. That tilt has historically produced different, sometimes better and sometimes worse, returns than the cap-weighted version, and it usually comes with higher volatility because smaller companies move around more.
Equal weight is not free, because it does not stay equal. Winners grow into oversized positions and losers shrink, so the portfolio has to be rebalanced back to equal on a set schedule, which generates trading costs and, in a taxable account, taxable gains.
The approach shows up well beyond fund management. Treasury teams spreading deposits evenly across approved banks, marketing teams splitting a test budget equally across channels and boards allocating capital evenly across divisions are all using the same logic: when you do not have a confident view on relative merit, refusing to pick favourites is a defensible default.
In practice
Real-world examples.
Example
An index provider launches an equal-weight version of a well-known large-company index because the parent index has become concentrated, with its ten largest members accounting for roughly a third of the total. The equal-weight version gives each of its 500 members 0.2%, so a single dominant company can no longer drive the headline number.
Example
A pension trustee board allocates across eight approved fund managers with no strong preference between them and gives each 12.5% of the mandate. Reviewing after two years, the trustees find one manager's share has drifted to 18% purely through performance, and they rebalance back to equal rather than let the drift stand as an unstated bet.
Example
A corporate treasurer with $24,000,000 of surplus cash and six approved counterparty banks places $4,000,000 with each. The decision is not about returns, which are nearly identical, but about capping the loss if any single bank fails.
Formula
Calculation
Weight of each holding = 1 / n, where n is the number of holdings
Amount invested per holding = total portfolio value / n
Equal-weight portfolio return = simple average of the individual holding returns
Consider a $500,000 portfolio built from five shares, so each holding is 1/5 = 20% and receives $500,000 / 5 = $100,000.
Suppose the same five shares also form a small cap-weighted index, with market values of $600bn, $200bn, $100bn, $60bn and $40bn, totalling $1,000bn. Their cap weights are therefore 60%, 20%, 10%, 6% and 4%. Over the year they return -5%, +10%, +20%, +30% and +40% respectively.
Cap-weighted return = (0.60 x -5) + (0.20 x 10) + (0.10 x 20) + (0.06 x 30) + (0.04 x 40)
= -3.0 + 2.0 + 2.0 + 1.8 + 1.6 = 4.4%
Equal-weighted return = (-5 + 10 + 20 + 30 + 40) / 5 = 95 / 5 = 19.0%
In dollar terms the equal-weight portfolio's five $100,000 positions end the year at $95,000, $110,000, $120,000, $130,000 and $140,000, a total of $595,000, which is the same 19% gain.
Rebalancing back to equal means each position should be $595,000 / 5 = $119,000. The manager sells $21,000 of the best performer, which sits at $140,000, and buys $24,000 more of the worst, which sits at $95,000, mechanically selling strength and buying weakness.Case study
Seen in the real world.
The following is a fictional, illustrative example. Kestrel Wealth Partners, an invented advice firm, ran a house model portfolio of thirty shares that it had built cap-weighted five years earlier and rebalanced only when clients asked. By the fifth year the three largest holdings had grown to 31% of the model between them, and a single one of them accounted for 14%.
Two of those three fell sharply in one quarter, and the model lost 9% while an equal-weight version of exactly the same thirty shares lost 4%. Nothing was wrong with the stock selection; the difference was entirely in the weighting.
The investment committee moved the model to equal weight at 1/30, or 3.33% per holding, with a rule to rebalance every six months or whenever a position drifted beyond 5%. They also documented the trade-off honestly for clients: more trading, a small tax drag in taxable accounts, and a permanent tilt towards the smaller names in the list.
Watch out
Common mistakes.
- Assuming an equal-weight portfolio stays equal without maintenance, when price moves push it steadily back towards concentration in the winners.
- Reading equal weight as automatically lower risk, when it usually raises exposure to smaller, more volatile companies and can be more variable than the cap-weighted version.
- Comparing an equal-weight fund's return to a cap-weighted benchmark and treating the gap as manager skill, when almost all of it comes from the weighting rule itself.
Questions
People also ask.
How often should an equal-weight portfolio be rebalanced?
Quarterly or semi-annually is common, because rebalancing more often adds cost while rebalancing less often lets concentration build back up.
Does equal weight always beat market-cap weighting?
No, it tends to do better when smaller companies lead and worse when a few very large companies do most of the work.
Is equal weight the same as diversification?
Not quite, because you can hold equal amounts of twenty companies in the same industry and still carry heavy concentration risk in that industry.
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