The KOSPI closed 17.91 percent higher on Friday, its largest daily gain on record, and retail investors sold into all of it

Three sessions of losses were taken back in a single day.

The KOSPI closed on Friday at 6,595.45, up 1,001.89 points or 17.91 percent, which The Korea Herald reports as the largest daily gain in the index's history in both points and percentage terms. It had shed more than 17 percent over the previous three sessions, a run this publication covered as it happened, including a trading halt on Wednesday and a second one on Thursday.

The open was ordinary. The index started 1.15 percent higher at 5,657.79 and then climbed into double digits, reaching 6,630.77 at its high, up 18.5 percent. A buy-side sidecar was triggered at 9:06 a.m., suspending program purchase orders for five minutes. The secondary Kosdaq market closed 11.63 percent higher at 719.76, which the Herald reports as its second-largest daily percentage gain.

Who was buying

Foreign investors bought a net 7.25 trillion won of KOSPI shares, about 5.06 billion dollars, a second consecutive day of net purchases after four sessions of selling. Institutions opened as net sellers, turned around the middle of the session and finished with net purchases of 1.15 trillion won.

Domestic retail investors were the other side of it. They sold a net 8.26 trillion won.

That is the reverse of the pattern this desk reported through the selloff, when retail buying met foreign selling. The Korea Herald reports foreign investors as net sellers of 18.5 trillion won of Korean stocks earlier in July, before the last two sessions.

The chip names carried it

Samsung Electronics closed 26.81 percent higher at 262,500 won. SK hynix finished at its daily upper limit, up 29.95 percent at 1,718,000 won, as did SK Square, which is SK hynix's largest shareholder, and Samsung Electro-Mechanics. Samsung C&T rose 19.56 percent, Samsung Life Insurance 17.99 percent and Hyundai Motor 10.54 percent. Biopharmaceutical names went the other way, with Samsung Biologics down 2.75 percent and Celltrion down 2.74 percent.

The overnight American session preceded it. The Nasdaq composite rose 2.78 percent and the Philadelphia semiconductor index rose 8.2 percent, after Microsoft reported its quarter on Wednesday evening.

Two named readings of why appear in the Herald's report and are worth separating from the arithmetic above, because they are opinion rather than record. Lee Kyoung-min, a senior analyst at Daishin Securities, is quoted saying that Microsoft and Amazon reaffirming capital spending plans eased concern about the semiconductor cycle, and that much of the forced selling had already been absorbed. A JPMorgan Korea equity strategy report published Friday is quoted saying the leveraged exchange traded fund unwind is complete and that hedge funds are done with around 90 percent of their deleveraging.

Neither claim is a document, and this item does not adopt either.