What Is a DLF (Derivative-Linked Fund)? How a German Bond Yield Wiped Out 98% of Investors' Principal

"German Bond Yields Could Go Negative?" — A Loss Nobody Had Priced In

In the second half of 2019, thousands of customers of two major Korean banks, Woori Bank and Hana Bank, opened their maturity notices and couldn't believe what they read. They had bought a fund expecting a return somewhat better than a bank deposit. Instead, one Woori Bank product linked to the 10-year German government bond yield, maturing on September 26, came back with a 98.1% loss. A comparable Hana Bank product matured with a 46% loss. Between the two banks, roughly 822 billion won (about $590 million at the time) of these funds and the securities inside them had been sold, 89% of it to individual investors. What made it worse: the banks kept selling — an additional 82.7 billion won went out the door even after the underlying rate had already started falling — and 48.4% of individual buyers were in their 60s or older. The product had been built on the assumption that German bond yields wouldn't fall deep into negative territory. That exact scenario happened, and the loss flowed straight back onto the people who'd bought in. This lesson covers what a DLF actually is, why a modest move in an interest rate could erase almost an entire principal, and how the fallout rewrote the rules for selling complex products to retail investors in Korea.

What a DLS and a DLF Actually Are: Same Family as an ELS, Different Underlying

As covered in what an ELS is, the basic design of a structured product is that the investor sells the issuer a put option and receives the premium back disguised as a "fixed coupon." Stay inside the agreed range and you keep the coupon; breach it, and you absorb the loss. A DLS (Derivative-Linked Security) uses that exact same design but swaps the underlying from a stock index for something else entirely: an interest rate, an exchange rate, a commodity price, or credit risk (whether a bond defaults). A DLF (Derivative-Linked Fund) takes it one step further — instead of holding the DLS directly, it's a fund (a collective investment vehicle) that holds a basket of DLS inside it. Rather than buying a brokerage-issued security directly, an investor buys into a fund that a bank or asset manager has built around that security. And in the 2019 case, the seller at the center of it all wasn't a brokerage — it was a bank. Woori Bank sold DLFs linked to German and British rates; Hana Bank sold ones linked to US and British rates. Most of these were structured as private placement funds, sold to a small number of investors at a time rather than offered publicly. That status came with lighter disclosure obligations than a public fund, which let the products move quietly and in concentrated volume through private banking (PB) desks at bank branches.

The Range-Barrier Structure: Why the Rate Had to Stay Inside a Line

The DLS inside the troubled 2019 DLFs used benchmark rates — the 10-year German government bond yield, or constant-maturity swap (CMS) rates in the US and UK — as their underlying. That's the same interest-rate variable covered in interest rate swaps, repurposed as the thing a structured product's payoff depends on. The mechanics were simple on paper: if the benchmark rate stayed inside (or above) a pre-set range at maturity, the investor collected a coupon of roughly 3-5% annually and got principal back. If the rate broke below that range, the loss wasn't proportional to how far it fell — it was multiplied by a pre-set loss multiplier, amplifying the damage far beyond the raw size of the move. A stock index would need something close to a systemic collapse of every listed company to approach zero. An interest rate has no such floor at all — it was simply assumed, going into the deal, that it "wouldn't realistically go that low." Sellers used that assumption to justify an attractively high coupon, and to investors, the pitch sounded like a safe, bond-like product. The catch was that because of the multiplier, even a small additional move past the barrier translated into a much steeper, non-linear jump in losses. A 1-2 percentage point swing in a benchmark rate is routine in bond markets — and here, that routine-sized move, leveraged through the multiplier, was enough to consume nearly the entire principal.

Here's a simplified, hypothetical version of that mechanism (not the actual terms of the 2019 products, just an illustration). Say the benchmark rate stood at 1.5% when the fund was sold, and the terms read: "pay a 4% annual coupon if the rate is at or above 0% at maturity; below 0%, multiply the shortfall by several hundred times to determine the loss." If the rate drifts down to 0.3%, the investor still collects the coupon and walks away. But if it drops just 0.3 more percentage points, crossing zero down to -0.3%, that same-sized move — leveraged through the multiplier — turns into a loss that wipes out most of the principal. A 0.3-point move in a bond yield is nothing unusual. What decided the outcome wasn't the size of the move, but which side of the line it landed on.

What Actually Happened in 2019: A Warning Nobody Sounded

In the first half of 2019, as the US-China trade war escalated and the European Central Bank signaled further easing, the 10-year German bund yield fell into deeply negative territory for the first time in its history. A scenario the products had been built to treat as remote became reality within months. What made it worse was that the two banks kept selling after the underlying rates had already begun falling — an additional 82.7 billion won went out during that window. Korea's Financial Supervisory Service later found that 48.4% of individual buyers (1,462 people) were 60 or older, and that the combined fees collected by the financial firms involved in selling these products came to 4.93% of the amount invested. When the dust settled, the Woori Bank product tied to German rates had matured with a 98.1% loss, and the Hana Bank product with a 46% loss. Regulators issued formal reprimands to Woori Financial Group's then-chairman Sohn Tae-seung and Hana Financial Group's then-vice chairman Ham Young-joo, and later dispute-resolution rulings granted compensation of up to 80% of losses in cases where mis-selling was found. What made the episode land so hard wasn't just the size of the losses — it was how many buyers said afterward that they'd believed principal was protected, or simply hadn't grasped how far the product could actually fall. Whatever loss conditions were buried in the product disclosures clearly hadn't come through at the point of sale.

Why a Bank Branch, of All Places: The Problem With the Trust Wrapper

An ELS is usually sold through a brokerage counter or a mobile trading app — and simply being at a brokerage carries an implicit signal that you're there to buy an investment product. The 2019 DLFs were different: they were sold at bank branches, wrapped as trust products. A customer who'd come in for a deposit or a wealth-management consultation would be steered by a private banker toward something pitched as "paying a bit more than a deposit." The sense of trust that a bank building itself conveys, combined with the word "trust" implying something you simply hand over for safekeeping, did real work in obscuring the fact that the product underneath was a high-risk instrument with embedded derivatives. If the Legoland ABCP crisis covered in commercial paper and ABCP was a story about the belief that "a provincial government guarantee means it's safe" collapsing, the DLF scandal was a story about a different kind of trust — "sold at a bank branch means it's safe" — breaking down in much the same way. Both episodes share the same underlying lesson: it usually isn't the product's structure alone that creates the danger, but the misplaced confidence that its distribution channel lends it.

The Aftermath: A New Regulatory Category Called "High-Risk Investment Products"

The scandal pushed Korea's Financial Services Commission to issue a comprehensive policy response in November 2019. At its center was a new category: products with embedded derivatives whose maximum possible loss exceeds a certain threshold and whose structure the average investor would struggle to understand, now classified as "high-complexity investment products" (고난도 금융투자상품). Banks and insurance companies were barred from selling private-placement funds and derivative-embedded trust products that fell into this category, though publicly offered high-complexity funds — which carry heavier disclosure obligations — remained permitted. A mandatory core-disclosure document became required for both public and private offerings alike. The rules were tightened again in October 2025: the FSC approved an amendment requiring the top of a product's disclosure document to explicitly state which customer profiles the product is unsuitable for, the possibility of loss, and past instances of actual losses, effective from January 2026. A separate ban now also targets sellers who steer a customer who received in-person consultation toward signing the contract online instead — a tactic that had been used to sidestep in-person disclosure obligations. If the 2019 response was about blocking certain products from certain sales channels, the 2025 revision is about making sure the risk is stated plainly up front, regardless of channel.

The Takeaway: Complexity and Distribution Channel Have to Be Checked Together

The lesson from the DLF scandal isn't "avoid every derivative-linked product." Structured products are a legitimate way to pursue returns above a deposit rate under specific conditions, and plenty of them pay out exactly as designed. The real lesson is that risk compounds when two things overlap. First, if an underlying's movement doesn't translate into loss directly but gets run through a multiplier, a scenario you were told is "unlikely" can turn out to be closer and more common than it sounded — and that's worth checking against the actual numbers, not the sales pitch. Second, where a product is sold, and the trust attached to that location, has nothing to do with how risky the product actually is. Being offered at a bank counter, under the label "trust," by a private banker, guarantees nothing about safety. What an investor can concretely do today is find the exact sentence in the core-disclosure document that answers "what's the maximum possible loss," and then ask whether that worst-case scenario has actually happened in recent years. In the DLF case, "German bond yields turning negative" was treated as an extreme, remote scenario at the time the product was designed — and it became reality within months.

Takeaway

• A DLF (derivative-linked fund) is a fund that holds DLS tied to non-equity underlyings — rates, currencies, commodities, or credit — built on the same design logic as an ELS, just with a different underlying asset.
• The 2019 products used a range-barrier structure where breaching a preset rate threshold triggered a loss multiplier, and when the 10-year German bund yield fell into unprecedented negative territory, Woori Bank's product matured with a 98.1% loss and Hana Bank's with 46%.
• The two banks sold roughly 822 billion won of these products (89% to individual investors), kept selling an additional 82.7 billion won after rates had already started falling, and 48.4% of individual buyers were 60 or older.
• These products moved through bank branches as private-placement funds and trust wrappers, and the trust attached to that channel played a real role in obscuring the derivative risk underneath.
• The scandal led to a new "high-complexity investment product" category that barred banks and insurers from selling high-complexity private funds, with a further rule — effective January 2026 — requiring loss potential and past loss cases to be disclosed up front.

FAQ

What's the difference between a DLS and a DLF?

A DLS (derivative-linked security) is the security itself, issued directly by a brokerage. A DLF (derivative-linked fund) is a fund that holds a basket of those securities. The payoff logic is identical either way — the only difference is whether you're buying the security directly or buying into a fund built around it.

Can you still buy these products at a bank today?

Since the 2019 policy response, banks and insurers in Korea are barred from selling privately placed funds or derivative-embedded trusts classified as high-complexity investment products. Publicly offered high-complexity funds, which carry heavier disclosure requirements, can still be sold through banks — and even then, the core-disclosure document's loss conditions are worth reading directly before buying.

Does a DLF always lose money?

No. As long as the underlying stays inside the agreed range, it pays a coupon better than a deposit rate, and plenty of DLFs have matured exactly that way without incident. The 2019 scandal happened because one specific underlying (German bond yields) moved far outside the range the product's designers had assumed, which is exactly the kind of risk that's built into this category of product and can, in principle, happen again with a different underlying.

⚠️ This article is for informational and educational purposes only and is not investment advice. The figures cited come from Korea's Financial Supervisory Service findings and contemporaneous reporting on the 2019 episode, and don't reflect the terms of any product currently being sold. Investment decisions, and their outcomes, are the investor's own responsibility.