'Why did you tell me to buy when it was expensive?' Hong Jin-kyung challenges ETF guru — who fires back with his '422 and 246' strategy

Park Min-su's new book lays out a 5-day ETF investing plan

ETFs seen as safer bet than volatile AI ecosystem stocks

The '2-4-6 strategy': buy more each time a position drops 20, 40 or 60%

The '4-2-2 portfolio': balancing defense and offense across three ETF buckets

Shipbuilding, defense, aerospace and biotech sectors also flagged as promising

[YouTube channel 'Study King Jjin Cheonjae Hong Jin-kyung']

Don't put everything into individual stocks — spread your assets across ETFs using the 4-2-2 portfolio. When the market shakes and ETFs pull back, that's when you deploy the 2-4-6 strategy and buy more. If you only try to avoid volatility, you'll miss the opportunity. But if you're prepared to use volatility, you can shout 'actually, this is great' even in a falling market.

As the prolonged slump in Samsung Electronics and SK Hynix drags on, retail investors who piled into semiconductor shares are growing increasingly anxious. The two stocks surged on the back of the AI boom but have since struggled to regain momentum, prompting some to lament that what they thought was a support level turned out to be anything but. Whether to cut losses now or buy more has become a pressing question.

That frustration was on full display in a recent YouTube clip that went viral. Broadcaster Hong Jin-kyung confronted Park Min-su — the investment author known online as "Choegoминsu" — saying she had started buying shares on his recommendation only to watch them keep falling. "Why did you tell me to buy when it was expensive?" she demanded. Park laughed and replied that the stock market is inherently difficult to predict.

Park is an investment specialist who has worked at a Yeouido securities-related institution for 28 years. In an interview Friday, he said the answer to today's volatile market lies not in prediction but in response. Rather than trying to call market tops and bottoms, investors should spread their assets through ETFs and follow a pre-set plan to buy more whenever prices fall.

Park, whose personal finance books have sold more than 100,000 copies, is back with a guide to ETF investing. His latest book, "ETF Investing in 5 Days," covers everything from ETF basics to stock selection, asset allocation and hands-on trading strategy. In the interview, he walked through his approach — from the "4-2-2 portfolio," which stages capital across three distinct ETF buckets, to the "2-4-6 strategy," which turns market declines into buying opportunities.

Cover of the new book 'ETF Investing in 5 Days.' [Dasan Books]

"The 4-2-2 ETF portfolio: balancing offense and defense" — Imagine yourself as a soccer manager taking the field with your assets. You cannot win by fielding 11 forwards. You need defenders to hold the line, midfielders to control the tempo, and strikers to go for goals. Park's approach to ETF investing follows the same logic, and he calls it the "4-2-2 portfolio."

The strategy divides assets into 40% in broad index ETFs, 40% in aggressive sector ETFs and 20% in covered-call ETFs. Rather than concentrating everything in the highest-returning products, the idea is to assign each ETF a distinct role so that stability and growth potential can be pursued together.

The first 40% goes into broad index ETFs tracking benchmarks such as the S&P 500 and NASDAQ 100 — the "defensive players" whose job is to track market-average returns steadily rather than beat the market. Among domestic indexes, Park said KOSPI 200 can serve as a long-term holding, while the Kosdaq 150 is better suited to short-term trading given its policy sensitivity and higher volatility.

He explained why 40% of the portfolio belongs in broad index ETFs: ETF structures periodically rotate out companies that lose their competitive edge and replace them with stronger ones. Tracking the market average steadily also helps reduce the fear of missing out on any single stock, he added.

The other 40% targets high-growth sectors such as semiconductors and robotics. Park suggested leading with semiconductors and robotics, then adding two or three sectors favored by investors — shipbuilding, defense and nuclear energy among them — to form an "attacking lineup" aimed at higher returns. He cautioned, however, that these sectors are more volatile than broad indexes, so investors need to manage them more actively, rotating into different sectors once a target return is reached.

The remaining 20% goes into covered-call ETFs to supplement cash flow, rounding out a lineup built to weather volatile markets. Park noted that first-generation covered-call products pay high distributions but fail to fully capture gains in the underlying asset. Second-generation products, which trim the distribution rate to around 10%, reduce the proportion of call options sold, which lowers payouts somewhat but allows investors to pursue both price appreciation and cash flow at the same time, he said.

Author Park Min-su, known online as Choegoминsu. [Provided by the subject]

"The 2-4-6 strategy: buy more when prices fall" — Once the 4-2-2 formation is in place, what should investors do when the market keeps sliding, as it has been lately? Park's second tactic is the "2-4-6 strategy." The approach calls for buying more each time a position falls 20, 40 and 60% from its peak. Rather than panicking and selling as prices drop, investors follow pre-set intervals to average down — and can afford to say "actually, this is great" in a falling market. The method has gained a following among retail investors under the name "the Choegoминsu investing method."

Park was clear, however, that the 2-4-6 strategy is designed for ETFs, not individual stocks. With individual stocks, a falling share price may reflect deteriorating company fundamentals, meaning repeated additional purchases could compound losses.

"When a broad index falls 20 to 40 percent, that is not a problem with any single company — it means fear has spread across the entire market," he said. "The ability to spread individual company risk is exactly why I prefer ETFs, and it is what makes the 2-4-6 strategy applicable."

On the view that US markets have lost some of their former upward momentum, Park said valuation pressure on high-flying AI technology stocks, compounded by mounting geopolitical uncertainty, has produced a wave of companies whose share prices fell sharply even after reporting strong earnings. He sees this not as a sign that AI's growth story is broken, but as the start of a process of separating the winners from the rest.

AI remains the core driver of US equity markets, he said, but the bar investors use to evaluate companies has risen sharply. For that reason, he doubled down on his view that in the AI era, ETFs are preferable to individual stocks. ETFs adjust their holdings and weightings as competitive dynamics shift, letting investors reduce the risk from any single company's underperformance while still riding the long-term growth of the technology revolution, he said.

"AI investment is currently concentrated in data centers, but the market that lies ahead is far broader," he said. "Physical AI such as robotics, on-device AI that runs directly on smartphones and other devices, and AI agents that act as personal assistants are all growing in succession." Sovereign AI — the push by individual countries to build their own independent AI ecosystems — would further extend the industry's long-term growth runway, he added.

forest@heraldcorp.com