◆ Stacks
KOSPI / VaR
메르 (ranto28) · 2026-08-08 · original: KO

When KOSPI Volatility Tripled, Foreign Risk Limits Tightened

Open in the Stacks app → Read the original ↗

VKOSPI rose from 30.6 on January 2 this year to 93.8 on June 30, roughly tripling.

When volatility grows, VaR swells, and holdings have to be reduced to stay within the risk budget already assigned. That means selling Korean stocks.

메르 · 2026.08.08 · translated from the Korean

The core point is that part of foreign selling can come from a risk-limit adjustment rather than a change in the fundamentals of Korean companies. Meru describes VaR as a loss budget that a portfolio is allowed to absorb. When volatility rises, the same equity holding is calculated as a larger risk. The fund can cut its position to stay inside a preset limit even when its view on the company has not changed. VaR shows a loss boundary for a chosen horizon and confidence level. cVaR, or Expected Shortfall, adds the average loss in the worst tail beyond that boundary. These measures are less a promise about the future than a common language for sizing portfolios.

An IMF analysis explains how VaR informs decisions to maintain, reduce, or increase positions, and how models that react quickly to higher volatility can create procyclical capital requirements ↗

The IMF describes VaR as a common language for maximum likely losses and for management decisions about whether positions should be maintained, reduced, or increased. Its 2009 analysis notes that a fast response to higher volatility can make capital requirements move in the same direction as the stress, pushing institutions toward simultaneous contraction. If this mechanism is active, foreign net selling cannot be read only as a long-term view on Korean equities.

The stretch that squeezed risk budgets

The original post says VKOSPI rose from 30.6 on January 2 to 93.8 on June 30. The index remained elevated in early August after the late-June peak. An annualized implied-volatility index is not the same thing as daily risk in a portfolio, but it can signal the direction in which a risk budget is being squeezed.

Single-stock leveraged ETF deposit10 million won
Cash-deposit rule30 million won
Leveraged ETF trade unit20 shares

Yonhap English independently confirmed the Korean authorities' rule change. It is an example of leverage-entry requirements rising during a high-volatility regime.

2026-07-24 · Yonhap English

The rule change alone cannot establish why VKOSPI fell. It does show that a market can have both a constraint on leveraged demand and institutions reducing holdings to fit a risk budget. Without the volatility signal, an observer may read every sale as a fresh change in the seller's fundamental view.

What to watch in the next foreign flow

This mechanism does not explain every foreign sale. Currency moves, earnings, policy, and cash repatriation remain separate variables. Still, comparing foreign net flows with VKOSPI and the won-dollar rate can help distinguish mechanical risk reduction from a changed outlook. The next check is whether foreign buying or selling, VKOSPI, and the won-dollar direction move together on the same days.

In three lines

Sources

  1. Original post Meru's explanation of VKOSPI, VaR, and foreign selling
  2. VaR and procyclicality Analysis of VaR models and capital requirements responding to higher volatility
  3. Single-stock leverage rule Cross-check of the deposit rule change

This author's record

44posts10directional calls8Bull2Bear3Hit2Miss
See the full record →