Jul 17, 2026 – 9.00amMelbourne/Tokyo | Every violent sell-off in South Korea’s chipmaker giants has become another buying opportunity for Sydney day trader Mark Olsen.Trading from his home office, Olsen has spent months piling into SK Hynix and Samsung Electronics whenever the shares plunge, often swinging by more than 10 per cent in a single session, as retail investors chase South Korea’s artificial intelligence boom with borrowed money.Subscribe to gift this articleGift 5 articles to anyone you choose each month when you subscribe.Subscribe nowAlready a subscriber? Fetching latest articles