At a Glance
Headline valuations such as an index-level PER or PBR appear to show at a glance whether the whole market is expensive or cheap, but in reality they are heavily distorted by concentration in a handful of large caps and by how earnings are calculated. Even for the same index, the multiple changes depending on which earnings figure you put in the denominator, and judging a market by a single average number can easily lead to misreadings.
The key is not the headline number itself, but breaking down how that number was constructed.
Why It Matters Now
As market capitalization has become concentrated in large technology stocks, index valuations have come to be driven by the multiples of just a few stocks (tickers). The S&P 500 is in a phase where the weighting of its top few stocks has climbed to historically high levels, so even if the index's overall PER looks high, much of that burden is concentrated in a few mega caps, while the valuations of the remaining stocks may be relatively low. It is a textbook case of the average masking the median.
Differences in the earnings basis amplify the illusion as well. The trailing PER (based on the past 12 months of earnings) and the forward PER (based on estimates for the next 12 months) paint different pictures when earnings growth is fast or slowing. Moreover, mixing GAAP earnings—which reflect one-off accounting charges and asset write-downs—with a company-adjusted operating profit basis can make the same market look expensive or cheap. There is also the effect whereby share buybacks reduce the share count, lifting earnings per share and making the multiple appear lower.
In a market like the KOSPI, where cyclical industry sectors such as semiconductors, automobiles, and finance carry a large weight, the sector composition itself drags the multiple down. The more industry sectors with high earnings volatility there are, the lower the PER tends to be, so it is hard to conclude a market is undervalued simply because the number is low.
Frequently Asked Questions
- If an index PER is low, is it always undervalued? No. A low multiple can be justified if there is a high weighting of industry sectors with volatile earnings, or if earnings are expected to slow going forward.
- Which should I look at, the trailing PER or the forward PER? You should look at both. If the forward PER is significantly lower than the trailing one, it means the market is assuming earnings growth, and if that estimate misses, the multiple burden resurfaces.
- Why is large-cap concentration a problem? Because when index valuations are driven by a few stocks, the market average fails to represent the actual condition of the majority of stocks.
- Which is correct, adjusted earnings or accounting earnings? Adjusted earnings strip out one-offs to reveal the underlying trend, but repeatedly excluding costs can inflate earnings, so you need to check the gap between the two measures.
Impact on Related Stocks and Sectors
- Mega-cap tech stocks (Nvidia, Apple, Microsoft): As the core pillar lifting the index multiple, changes in their earnings estimates drive the interpretation of index valuations.
- Semiconductor sector: Because the earnings cycle is steep, the gap between trailing and forward PERs is wide, making it hard to judge over- or undervaluation from headline numbers alone.
- Finance and banking: Traditionally a sector with low PBR, where a low multiple may reflect sector characteristics rather than undervaluation.
- Cyclical export stocks such as automobiles: Owing to earnings volatility and the business cycle, they act as a factor dragging down the KOSPI's overall multiple.
- High-dividend and buyback stocks: A falling share count improves per-share metrics, which can make the multiple look lower than it actually is.
Points to Watch When Investing
- Check not only the index average PER but also the median multiple excluding the top stocks, to strip out the concentration effect.
- Even within the same market, specify the trailing-vs-forward and GAAP-vs-adjusted earnings basis to align what is being compared.
- Be wary of simplistic cross-country multiple comparisons that ignore differences in sector composition.
- Use valuation as a tool for checking risk and expected return, not as a market-timing indicator.
Overall Outlook
Investors who break down headline valuations can avoid the simplistic conclusion that the market is uniformly expensive or cheap. If we are in a phase where, excluding the large caps, the multiples of most stocks are below the average, there is room for re-rating opportunities to open up in overlooked stocks once the concentration eases. Conversely, if the index's gains rely on high earnings expectations for a few stocks, the average multiple can quickly turn into a burden when those estimates wobble. Ultimately, regularly checking the change in earnings estimates heading into the next earnings season, the market-cap weighting of the top stocks, and the gap between forward and trailing PERs is the way to avoid being swayed by headline numbers.
This article is content automatically summarized and analyzed based on the original news. View original (Yahoo Finance)
