Why some stocks soar tenfold when most don't: the secret of 'ten-baggers'

Had you invested 10 million won ($6,430) in Wonik Holdings at the start of last year, you would have ended the year with 190.98 million won. The same sum put into Cierus (formerly Cierus Technology) would have grown to 123.79 million won, and into Robotis, 115.28 million won. In each case, the original investment multiplied more than tenfold in a single year.

In stock market parlance, a stock that returns ten times the original investment is called a "ten-bagger" — a term coined by legendary American fund manager Peter Lynch and a figure every investor dreams of hitting at least once.

Ten-baggers are rarer than most people think. On the Kospi last year, 647 of 948 listed stocks rose while 288 fell. On the Kosdaq, 954 of 1,723 stocks advanced and 729 declined. In total, 1,601 stocks posted gains.

Yet only three — Wonik Holdings, Cierus and Robotis — multiplied an initial investment tenfold or more. In 2024, not a single ten-bagger existed.

All three traded in the same market and rode the same bull run. So why were these three companies alone able to become ten-baggers?

Many investors watch charts — looking for when trading volume surged, when foreign buyers moved in, when a stock broke to a new high.

But tracing the path of last year's ten-baggers reveals a common thread. The industry shifted first, then the earnings outlook changed. Brokerages reflected those changes in their research notes, and the market repriced the companies accordingly.

Cierus, a medical AI specialist, is the clearest example.

On Feb. 7 last year, Daol Investment & Securities published its first research note on what was then called Cierus Technology. At the time, medical AI was widely respected for its technology, but whether it could translate into actual sales and profit remained unproven. For investors, the central question was simple: can good technology make money?

The report focused on answering that question. Titled "First to profitability — FDA approval also in sight," it framed Cierus's ability to turn profitable ahead of rival medical AI firms as the key investment thesis, set a target price of 28,000 won and forecast that "2025 will be the first year of annual profitability."

The foundation of that argument was thynC, Cierus's flagship service — an AI-based remote monitoring platform that analyzes patients' electrocardiograms, respiration and blood-oxygen levels around the clock and relays the data to medical staff in real time. The more hospitals adopted it, the more recurring subscription revenue would accumulate.

A month later, in March, SK Securities also initiated coverage of Cierus with a target price of 34,000 won, calling it "the AI healthcare company closest to monetization."

The analytical focus sharpened further. Where the February note had highlighted the possibility of turning profitable, the March note explained the structure behind that profitability — the general-ward monitoring market was opening up, and recurring revenue would grow in step with each new hospital that adopted thynC.

By July, the numbers had changed dramatically. On July 11, Daol Investment & Securities retitled its report "Full potential unleashed" and raised its target price to 50,000 won.

The key driver was a sharp revision to the earnings outlook. Daol raised its 2025 sales forecast for Cierus from 21.5 billion won to 31.8 billion won and its operating profit forecast from 2.8 billion won to 9.2 billion won — more than tripling the profit estimate — after concluding that thynC-equipped hospital beds were expanding faster than expected.

From October onward, the language shifted again. Samsung Securities described Cierus as an "all-in-one digital healthcare" company; Shinhan Investment titled its note "Just Beginning." By year-end, Shinyoung Securities was using the phrase "ten-bagger medical AI company" outright.

The market's lens had evolved in stages: first, "can it make money at all?" (the path to profitability); then, "does it earn steadily?" (recurring revenue); and finally, "how fast is it growing?" (bed expansion). As conviction grew that the company could generate sustainable earnings, target prices rose in tandem.

Robotis is now regarded as a flagship humanoid robot stock. But early last year, the investment case brokerages made for the company centered not on humanoid robots but on actuators — the components that serve as the joints and muscles of a robot, with a typical humanoid requiring 40 to 50 of them.

On Jan. 9 last year, Stunning Value Research argued that "actuator technology has entered full-scale commercialization," citing the open manipulator "OM-Y" jointly developed by Robotis and MIT, as well as the company's entry into Japan's delivery robot market. At the time, the market's focus was less on the humanoid robot boom than on whether actuator technology could translate into real business.

By Feb. 7, the investment thesis had grown more concrete. SK Securities set a target price of 63,000 won and wrote that "2025 is the year initial supply begins — not just test volumes." The conversation had shifted from evaluating technology to forecasting actual supply and sales.

Earnings estimates followed in May. Hana Securities noted that Robotis had posted first-quarter sales of 10.1 billion won and operating profit of 800 million won — a faster-than-expected return to profitability. It forecast full-year 2025 sales of 45.8 billion won, up 52.6 percent from the prior year, with operating profit of 4.5 billion won marking a swing to the black. Actuator sales alone were projected to reach 40 billion won, driven by an expanding overseas customer base and the start of full-scale supply to Chinese humanoid robot makers.

In the second half of the year, the language brokerages used to describe Robotis also changed. In June, Shinhan Investment called it "the prime beneficiary of humanoid robot mass production." In August, Hyundai Motor Securities wrote that "actuators are to the robotics industry what GPUs are to the AI industry" — meaning that just as Nvidia had reaped the greatest rewards by supplying graphics processing units to the AI sector, the maker of the critical component in humanoid robots stood to benefit most.

In November, Daishin Securities published a report titled "The Age of Great Transformation," setting a target price of 270,000 won. Analyst Lee Ji-ni wrote that "actuators are the core of physical AI" and forecast that a shrinking working-age population and the automation of manufacturing would drive Robotis's long-term growth.

First the market looked at the technology. Then it looked at supply, then at earnings. By year-end, it had begun to assess Robotis's corporate value within the broader industrial current of physical AI.

Wonik Holdings's story was somewhat different. It did not attract the flood of research notes that Cierus did, nor was it a marquee thematic stock the way Robotis was. Instead, the market began to see Wonik Holdings not as a simple holding company but as a vehicle carrying the value of its semiconductor and AI robot subsidiaries — including Wonik Robotics's AI robots and key affiliates Wonik IPS and Wonik Materials — as those units drew growing attention.

The same pattern is playing out this year. Jusung Engineering has surged 773.65 percent, Samsung Electro-Mechanics 764.71 percent and SK hynix 293.24 percent. All three share a common thread: amid the spread of AI, their earnings outlooks and target prices have been raised repeatedly, prompting the market to revalue them. Samsung Electro-Mechanics has benefited from rising demand for multilayer ceramic capacitors and AI package substrates driven by AI server expansion. SK hynix has seen its earnings estimates and target prices climb steadily on the strength of HBM. Jusung Engineering is being recognized as a key beneficiary of AI semiconductor processes, with next-generation atomic layer deposition and through-glass via equipment emerging as new growth drivers.

None of this means these companies are certain to become ten-baggers this year. But the pattern last year's ten-baggers shared was clear: the industry shifted first, and that shift fed through into higher earnings forecasts. The market used those revised estimates to reprice corporate value, and share prices moved in step. Ten-baggers were born in the process of industry change being reflected in earnings estimates and corporate value being reassessed.

Legendary American fund manager Peter Lynch put it this way: "Investing in stocks without studying the companies is the same as playing poker without looking at your cards."