KOSPI closes at 6,813.34 on August 13, 2026 — but KOSDAQ managed only 0.29%

Two days earlier this page reported that the KOSPI had gained 233 points in a single session. On August 13 it did it again — 234 points.

6,813.34. Up 3.56%. Measured from the August 11 close of 6,345.53, that is 467.81 points, or 7.37%, in two sessions.

On the same day the KOSDAQ rose 0.29%. The distance between those two numbers is the whole story.

1. The numbers

The KOSPI opened 194.88 points above the previous close. That gap was not built during the session — it was set before the bell, by what happened overnight in New York. US July consumer prices came in at 3.4%, and the S&P 500 set another record close.

The intraday high of 6,895.63 left the index 21 points short of 6,900. It finished 82 points below that high.

The won closed at 1,419.40 to the dollar, weaker by 3.7 won. A 3.56% equity rally that coincides with a weaker currency says foreign buying was either not large enough to move the currency, or was offset by flows in the other direction.

2. Two stocks did the work

When the two largest constituents both outperform the index, arithmetic requires that most of the rest underperformed it. The KOSDAQ's 0.29% confirms it.

Three sessions earlier the picture was inverted. On August 10 the KOSDAQ surged 6.97%, driven by retail buying even as foreigners sold 1.49tn won on that board. By August 13 the flow had crossed over: retail selling, foreign buying, and foreign buying goes into large-cap memory.

3. Flows — and why the numbers disagree

That is one outlet's tally. Others put foreign net buying at 2.12tn, 2.4tn and 3.71tn won; institutional buying is reported as both 682bn won and 6.8bn won. A 1.6tn won spread is not rounding — it is a difference in what is being counted. Main board only, or KOSDAQ, basket and off-exchange trades as well? That could not be confirmed.

What every tally agrees on: foreigners bought for a third straight session, the first such run in August, and retail sold more than 2tn won for a second consecutive day.

4. What drove it — and what has not been filed

Cooler US inflation. The July CPI print released overnight came in at 3.4% headline and 2.5% core, softening the case for a September Federal Reserve hike. That relief travelled through New York into the Seoul open.

AI chip demand, re-confirmed. Stronger-than-expected results from US AI infrastructure names revived memory demand forecasts. Korean customs data showing semiconductor exports up 155% year on year in the first ten days of August pointed the same way.

There is a third driver being cited daily, and it is worth separating from the first two. Markets are positioning for expanded shareholder-return programmes from Samsung Electronics and SK Hynix. Reports suggest an announcement could come in August. As of August 13, nothing has been filed. This expectation has now been named as a reason for gains on three separate sessions without a single disclosure behind it.

And a timing note that matters for reading this session correctly: US July producer prices were released on the night of August 13, Korea time — after the Seoul close. The 3.56% does not contain that result.

5. What is unresolved

Over two sessions the KOSPI gained 7.37%. Over the same stretch the KOSDAQ put in one 6.97% day and then stopped. One market is running at two speeds, and the dividing line is whether a portfolio holds large-cap memory.

The flow figures are not settled here. Whether foreigners bought 2tn or 3.7tn won changes how much staying power this rally has — but with the tally basis unconfirmed, reporting the spread is more honest than picking one number.

One more scheduling item for anyone trading this market. August 15 is Liberation Day and falls on a Saturday, so Monday August 17 is a substitute holiday and Korean markets are shut. The next Korean session after Friday August 14 is Tuesday August 18. New York trades on both August 14 and August 17 in that window — two US sessions accumulate where a normal weekend would leave one.