Fundamental-Weight Rebalancing
Weight companies by business fundamentals instead of market enthusiasm
- Difficulty
- Moderate
- Time to result
- ~ongoing to results
- Steps
- 6
- Confidence
- 99%
Fundamental weighting constructs a rules-based index using company measures such as earnings or dividends rather than market capitalization. A capitalization-weighted portfolio automatically assigns more weight as a stock's price rises, which becomes dangerous when enthusiasm pushes price far beyond business fundamentals. The fundamental portfolio instead calculates each company's economic weight and periodically compares that weight with its market price. If fundamentals improve without a matching price increase, the formula buys more; if price outruns fundamentals, it trims the position. Because the inputs and schedule are predetermined, the method remains passive in operation while embedding a value-oriented rebalancing mechanism. Low-frequency rebalancing limits taxes, transaction costs, and unnecessary trading.
Origin
After the dot-com crash exposed capitalization weighting's concentration problem, Jonathan Steinberg invited Siegel to evaluate earnings- and dividend-weighted indexes that later became part of WisdomTree.
Core principles
- 01Price alone should not determine a company's portfolio weight
- 02Use objective fundamentals rather than discretionary forecasts
- 03Rebalance systematically when prices diverge from fundamentals
- 04Keep turnover, taxes, and fees low
- 05Apply the formula consistently through market cycles
How to run it
- 1
Choose the fundamental
Select an objective measure such as earnings, dividends, sales, or a documented combination. Define how negative or missing values will be handled.
Pro tip Prefer fundamentals with consistent definitions and reliable historical data.
Watch out Changing the measure after seeing performance turns the process into backtest selection.
- 2
Define the universe
Specify which securities qualify and when constituents enter or leave. Keep eligibility rules independent of subjective price forecasts.
Pro tip Use liquidity and investability screens before calculating weights.
Watch out A poorly defined universe can introduce hidden survivorship or liquidity bias.
- 3
Calculate economic weights
Determine each company's proportion of the universe's selected fundamental. Use those proportions as target portfolio weights.
Pro tip Document the formula so another analyst can reproduce every weight.
Watch out Do not quietly override inconvenient outputs with discretionary judgments.
- 4
Compare fundamentals with price
Identify companies whose fundamentals rose faster or slower than their market prices. This divergence drives the eventual rebalance.
Pro tip Review sector concentration before executing the targets.
Watch out Fundamental cheapness can persist and does not guarantee an immediate recovery.
- 5
Rebalance systematically
On the scheduled date, buy companies whose fundamental weight exceeds their portfolio weight and trim those whose price has outrun fundamentals.
Pro tip Annual rebalancing can capture the mechanism while limiting friction.
Watch out Frequent rebalancing can consume the expected advantage through costs and taxes.
- 6
Evaluate the full outcome
Compare risk-adjusted return, turnover, fees, taxes, and tracking error with a capitalization-weighted benchmark. Judge the method over complete market cycles.
Pro tip Separate gross factor performance from the investor's net realized result.
Watch out Do not abandon the method after a short period of underperformance.
In the wild
Technology share prices surge while their aggregate earnings do not keep pace. At the annual rebalance, an earnings-weighted index reduces those companies because their prices have risen relative to their economic contribution, redirecting weight toward companies with stronger earnings relative to price.
→ The portfolio avoids becoming mechanically dominated by the most expensive sector.
A mature company maintains strong dividends while its share price stagnates. Its dividend share of the index becomes larger than its current portfolio weight, so the next formulaic rebalance purchases additional shares.
→ The portfolio adds relative value without requiring a manager to forecast the company's price.
Common mistakes
Calling price weighting neutral
Capitalization weighting is itself a weighting choice and can concentrate the portfolio in securities whose prices have risen furthest.
Rebalancing too frequently
Excessive turnover creates transaction costs and taxes that can erase the method's expected advantage.
Adding discretionary overrides
Subjective exceptions undermine the reproducibility and passive character of the formula.
Is it for you?
Best for
It is best for long-term index investors who want systematic valuation discipline without discretionary stock picking.
Not ideal for
It is not ideal for investors seeking exact market replication, minimal tracking error, or zero rebalancing turnover.
From the transcript
“What you do is it's on the basis of just objective data on the earnings. We don't make any judgment whatso weather on whether the…”
“You know, if the fundamentals moved up but the price didn't, we buy more of it. The fundamentals moved down, we buy less of it.”
“I think fundamental waiting is one way that does it for you, by the rebalancing technique.”
From the episode
An Interview With Jeremy Siegel: Masters in Business (Audio)