Today, Korea’s KOSPI fell 5.35% in a single session — the kind of day when a fund following strict strategic asset allocation rules is supposed to step in and buy. Passive funds that commit to a fixed rebalancing rule are built to do exactly that: when an asset class drops below its target weight, the rule forces a purchase, no matter how anyone feels about the market that day. That’s one of the quiet benefits of following a rule instead of a judgment call — panic turns into a scheduled purchase.
Today, Korea’s National Pension Service didn’t buy. It sold.
The reason traces back to strategic asset allocation itself — a target weight for each asset class that a fund commits to for the year, with a tolerance band around it. Think of it as a recipe: domestic stocks at roughly 15% of the portfolio, give or take a few points. When the market pushes an asset above or below that band, the rule is supposed to kick in automatically — no debate, no vote, just execution.
The problem is Korea’s fund didn’t just adjust within the band this year. It rewrote the target itself, twice. In January 2026, the domestic equity target moved from 14.4% to 14.9%. In May, it jumped again, to 20.8%.
There’s a precedent, and it isn’t reassuring. In April 2021, the fund widened its tolerance band from ±2 to ±3 percentage points but left the actual target alone. Even that smaller move was followed by a rough year — when Korean stocks fell in 2022, the fund’s domestic equity return came in near -22.7%. This year’s change goes further: it’s not the band that moved, it’s the target.
With that target now sitting near the top of its own range, the fund has little room left to buy on a day like today — which is exactly why the rebalancing floor that used to soften crashes wasn’t there.
None of this is unique to a pension fund. A stop-loss rule only holds up if it survives the day it becomes inconvenient — the same logic behind why the Fed kept moving its own inflation goalpost instead of admitting the target wasn’t working.
My take: Even a leviathan like the National Pension Service turns out to be just another ant when the rule gets inconvenient.
Not advice. Just how I see it.