Equal-Weight Index: Every Stock Gets the Same Slice

The fact sheet for a hypothetical fund lists its weighting method on one line: “Equal weight, rebalanced quarterly.” Two lines down, the top holdings are nearly identical in size. On a cap-weighted fund tracking the same list of companies, that table would read very differently, with the biggest names taking a large slice at the top.

The same stocks, two different returns

Take a hypothetical index with only three members. Stock A is worth $600 billion. B is worth $300 billion and C $100 billion, for a combined $1,000 billion. Over one period A returns +10%, B returns 0% and C returns -20%.

Same three stocks, and a gap of more than seven points.

The difference comes entirely from how much money sits in each name. The cap-weighted index put most of its money in the winner because the winner was already the biggest, while the equal-weighted version gave the smallest stock, the one that fell 20%, as much say as the largest. Reverse the returns and the result flips: the equal-weight index would come out ahead. Neither method is correct in general. Each is a bet about which part of the list does better.

Rebalancing and turnover

Weights do not stay equal. Put $10,000 into the equal-weight version.

The rebalance sells what gained ground and buys what lost it. Every rebalance does that.

That habit is the reason equal weighting tilts toward smaller members, and it is also the reason turnover runs higher than in a cap-weighted fund, where a rising stock’s weight simply rises with it and nothing needs to be traded. Trading costs and spreads come with that turnover, and so do realized gains if you run the same scheme yourself in a taxable account; inside a fund you won’t see the trades, although the fact sheet or annual report usually states a turnover figure you can compare.

Reading it on a fund fact sheet

A few lines on the fact sheet do most of the work. The weighting method names the approach. The rebalance schedule tells you how far weights can drift between resets. The top holdings table shows how equal things are today.

Look at the sector breakdown too. Equal weighting gives each sector a share in proportion to how many members it has, so a sector with many small companies gets more weight than its market value would give it, and a sector dominated by a few giants gets less.

What people get wrong

A common mistake is assuming an equal-weight fund removes concentration risk. It removes concentration in the largest names. It adds exposure to the smallest. The case about index fund concentration explains why that trade can still be worth making, even though it can leave a portfolio heavy in whichever sector happens to have the most members on the list.

Another is comparing an equal-weight fund with its cap-weighted twin over one short stretch. One method always leads. The lead mostly reflects which end of the list did better.

The last mistake sits in your own account. Holding a cap-weighted index fund alongside a handful of single stocks can leave you with far more in one company than you intended, because the fund already holds it at its full market weight. Run your holdings through the position concentration calculator to see the combined share, and compare it with a cap you set in advance, as worked through in how much of your portfolio one stock should be.

Related terms

Cap weighting is the default for most broad indexes, including the S&P 500. Float adjustment trims a company’s weight to the shares actually available to trade. A capped index sits between the two. More index terms are in the investing hub.