The point
On 6 November 2026 the Kospi fell about 9% and the Korea Exchange halted trading for 20 minutes. Samsung Electronics and SK Hynix together make up nearly half of the index, so the fall was led by two names. An index of hundreds of stocks can behave like a position in two. Whether it does is set by the weighting rule.
What happened to the Kospi on 6 November 2026?
The Kospi, South Korea's benchmark index, plunged about 9% on 6 November 2026 and dropped below 5,000 points for the first time in nine months. The Economic Times reported that the Korea Exchange suspended trading for 20 minutes shortly after the open, when the index was down as much as 8.8%.
The sell-off followed a rout in the US on 5 November 2026, when the Nasdaq 100 fell 6.4% and lost a record $2.3 trillion in market value. Samsung Electronics and SK Hynix led the Korean fall. Both dropped more than 11% in early trade before recovering part of it.
The Economic Times also reported that the Kospi had nearly tripled in the year to its June peak, driven by expectations of higher earnings at those two chipmakers. It has since fallen around 46% from that record high.
Source: The Economic Times, report last updated 6 November 2026 at 09:52 IST, https://economictimes.indiatimes.com/markets/us-stocks/news/ai-meltdown-kospi-crashes-9-hits-9-month-low-as-wall-street-bloodbath-after-midterm-elections-spills-to-asia-circuit-breaker-triggered/articleshow/135591355.cms, read 7 November 2026.
What is the Kospi, and why is it so concentrated?
The Kospi is the price index of the main South Korean stock market. The Kospi 200 is a narrower version built from 200 large companies. Both weight each company by its market value, so a company that gets bigger than the rest takes a bigger share of the index without anyone deciding it should.
A Korea Economic Daily report, republished by Bloomingbit, puts numbers on the Kospi 200. Samsung Electronics is about 33.1% of it and SK Hynix about 26.5%. Together that is 59.6%. The third-largest holding is under 3%. The page carries no publication date, so treat the figures as the report's reading as of 7 November 2026, when this piece read it.
Two different measures sit side by side here. The Economic Times says the two stocks are nearly half the Kospi's total weight. Korea Economic Daily says they are 59.6% of the narrower Kospi 200. Either way, the other 198 names share what is left.
A count of stocks is a marketing number. The weight table is the real portfolio, and it is the first thing to read in any index.
Source: Korea Economic Daily via Bloomingbit, undated page, https://en.bloomingbit.io/feed/news/117730, read 7 November 2026.
Mechanism 1: market-value weighting lets the winner grow its own share
When an index weights by market value, a stock that rises faster than the rest becomes a larger part of the index at the next reading. Nobody chooses that. The rally in two chipmakers raised their weights, and each rise made the index more dependent on them.
The Economic Times added that the run-up drew a wave of individual investors and that leveraged exchange-traded funds linked to the two chipmakers grew too. The index fell hard for the same reason it had risen: it was leaning on those two names.
Mechanism 2: a weight cap is a rule somebody has to write
A weight cap says no single holding may exceed a stated share of the index. Korea Economic Daily lists the caps used elsewhere.
- The Nikkei 225 limits any single stock to a maximum weight of 10%.
- The Nasdaq-100 caps individual weights at 24% and limits the combined weight of stocks above 4.5% to 48%.
- The NYSE 100 limits individual weights to 20%, and Russell indexes apply caps of about 20%.
- The Kospi 200 has no separate ceiling on individual weights, according to the same report.
Source: Korea Economic Daily via Bloomingbit, https://en.bloomingbit.io/feed/news/117730, read 7 November 2026.
Korea did once have a cap. The Asia Business Daily reported on 2 April 2020 that the Kospi 200 restricted any single stock to 30% when selecting constituents. Samsung Electronics stood at 33.07% on 31 March 2020. The exchange was asking institutions for views on removing the cap, with comments open until 22 April 2020.
That article is where the trade-off shows. It reported that applying the cap would have forced funds tracking the index to sell about KRW 500 billion of Samsung Electronics shares. Exchange-traded fund assets tracking the Kospi 200 stood at about KRW 17 trillion. That is about 3% of those assets. A cap protects against concentration and also forces sales on a schedule, so the rule has to say when.
The 2020 article does not say how the consultation ended. The later Korea Economic Daily report says the Kospi 200 has no separate cap.
Source: Asia Business Daily, 2 April 2020, https://www.asiae.co.kr/en/article/2020040212061072057, read 7 November 2026.
Mechanism 3: the rebalance schedule decides when a cap bites
A cap works only on the dates it is applied. If weights are reset once a year, a stock can run far past the cap in between. If they are reset monthly, drift is trimmed faster, and the index sells winners and buys laggards in small steps instead of one large sale.
That is why three questions come before any index: who sets the weights, how often, and where the rule is published.
How big is the exposure, with the arithmetic?
Take a ₹25 lakh position in a fund that follows the Kospi 200 weights above. This is an illustration of arithmetic, not a forecast and not a statement about any fund's actual holdings.
- Samsung Electronics and SK Hynix: 59.6% of ₹25,00,000 is ₹14,90,000.
- The other 198 stocks: 40.4% of ₹25,00,000 is ₹10,10,000.
- The third-largest holding, at under 3%: under ₹75,000.
Now suppose both chipmakers fall 11%, which is what they did in early trade on 6 November 2026. ₹14,90,000 times 0.11 is ₹1,63,900. That is 6.56% of the whole ₹25 lakh position, and it comes from two names before any other holding moves.
Compare an index with a hard cap of 15% on any holding. Two names at the cap would be 30% of the position, or ₹7,50,000. The same 11% fall on those two names is ₹82,500, which is 3.3% of the position.
What a cap limits is how much of a fall any one name can cause.
How does the same question apply to a crypto index?
A crypto index has the same three questions. If it weights by market value, the largest coin sets the largest weight, exactly as Samsung Electronics does in the Kospi 200. If it caps weights, a rule says by how much and when the cap is applied.
Qatobit's indexes answer these in writing. The crypto indexes are rebalanced monthly on a published methodology. The weights are published on the home and index pages, so anyone can work out how much of each asset a given amount buys. Around each rebalance the investor can see what was sold and what was bought.
QSI GEQ8 holds eight global companies rather than crypto. Its methodology sets weights by free-float market value adjusted by a quarterly score, with hard caps: no holding above 15% or below 3%. It is rebalanced monthly, with a quarterly composition review.
The caps are documented for GEQ8. For the crypto indexes, the index pages are where the weights and rules live, and they are worth reading before a position is sized.
What should you check in any index before you hold it?
Read the top two holdings and add them. If two names are more than a third of the index, the count of holdings tells you little.
Then check the rule. Is there a cap, who set it, and where is it published? Check the schedule next: how often the index resets, and what it sells when it does.
The Kospi shows what an index does when the answers are "no cap" and "market value decides". Sized as a share of a portfolio, a position in an index like that carries a single-stock risk, whatever its name says.
For related reading, what a crypto index is explains how a basket is built, and concentration risk covers how a few holdings can decide the outcome of a whole portfolio. Portfolio rebalancing after a holding falls is worked through step by step, and asset allocation sets how much of a portfolio any one index should be.
Frequently asked questions
Why did the Kospi fall 9% in one session?
The Economic Times reported a chip and technology sell-off that followed a 6.4% fall in the Nasdaq 100 on 5 November 2026. Samsung Electronics and SK Hynix fell more than 11% in early trade, and they are nearly half the index's weight, so the index fell about 9%.
How much of the Kospi do Samsung Electronics and SK Hynix make up?
The Economic Times says nearly half of the Kospi's total weight. Korea Economic Daily reports 33.1% for Samsung Electronics and 26.5% for SK Hynix in the Kospi 200, which is 59.6% together.
What is a weight cap in an index?
A weight cap is a rule that no single holding may exceed a stated share of an index. The Nikkei 225 caps a single stock at 10%, and the Nasdaq-100 caps individual weights at 24%, according to Korea Economic Daily.
Does a weight cap stop an index from falling?
No. A cap limits how much of a fall one holding can cause. On a ₹25 lakh position, two holdings at a 15% cap and falling 11% cost ₹82,500, against ₹1,63,900 for two holdings at 59.6% combined.
What should I check about a crypto index's weights?
Check who sets the weights, how often they reset and where the rule is published. Qatobit's crypto indexes are rebalanced monthly on a published methodology, and the weights are published on the home and index pages.
Crypto investments are subject to market risk. Not financial advice.
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