Stock Investing Guide

This is a guide I hope will help beginners. It's a compilation of lessons learned from over 10 years of stock investing.

1. Know Yourself Before You Invest

Investment Style: Conservative VS Thrill-Seeking

What you need to know when investing in stocks:

Investment styles can be broadly divided into conservative and extreme-risk (thrill-seeking). The conservative extreme is the realm of guaranteed principal, such as savings accounts and fixed deposits. Since buying stocks itself is an act of taking on risk, the moment you step into the market, you're standing somewhere in the middle of this spectrum. Within that range, there's everything from relatively safe approaches like index fund dollar-cost averaging to extreme high-risk-high-reward tactics like scalping or going all-in on a single stock. That said, ultra-short-term trading is a domain only the top 1% can survive in, and it requires natural talent.

Most people fall somewhere between these two extremes. That's why you need to first figure out where you stand and find a method that suits you.

The reason this ratio matters is that it directly becomes your portfolio allocation. It varies with market conditions, but I typically operate somewhere between conservative 2 : thrill-seeking 8 and conservative 4 : thrill-seeking 6.

Before deciding your investment approach, you need to first assess your current situation and temperament. If you're the thrill-seeking type, you'll naturally shift toward a higher conservative allocation as your wealth grows.

Risk Tolerance: How Much Can You Handle?

Risk tolerance means how much loss you can endure while still making rational decisions. Once you exceed this limit, fear takes over and you start panic trading, unable to follow your own rules.

You must view losses as percentages (%), not dollar amounts. A $1,000 loss is 10% of $10,000 but only 1% of $100,000. Dollar amounts shake your emotions, but percentages let you think clearly. In my case, regardless of portfolio size, -25% is my limit. When my portfolio was $50,000, -25% was the point where I could still hold my composure and trade according to my rules without panic selling.

If you don't know your limit, you'll take positions you can't handle. When the market crashed, I panic-sold, but I should have waited until I could think clearly, even if it meant losing more. Fortunately, I followed my rule of only selling half rather than the entire position, which gave me an opportunity to re-enter when the market recovered.

Market downturns always happen. You must know your risk tolerance limit in advance and only take positions within that limit; that's how you maintain discipline even when fear strikes.

Risk tolerance can only be learned through direct experience. You have to pay your tuition to the market. I learned by losing significant money, but the best approach is to fail many times with small amounts.

• Paper trading: No real money at stake, so you can start without pressure
• Invest under $1,000: You need real money on the line to experience genuine market psychology

Through this process, you'll agonize, struggle emotionally, and simultaneously build up successful experiences step by step. As you clear the psychological hurdles of risk and gradually expand the range you can tolerate, you'll discover the strategies that work for you and the level of risk you can actually handle.

You Need to Set a Target Return

Once you know your investment style and risk tolerance, the next step is setting a target return. Without this, you can't decide what to buy or how to structure your portfolio. For long-term investing, just setting an annual target return is enough. For a longer view, you can break it down into 10-year / 5-year / 1-year / monthly targets.

Your target return determines which products to choose. Investment products ranked by risk level look like this:

Index ETF < Sector ETF < Individual Stocks < Leveraged ETF < Futures/Options

If your target is 10% annually with a long-term horizon, index funds alone are sufficient. Many people actually invest using only index funds. The advantage of index investing is that you can adjust for any style using leverage multipliers: 3x for short-term, 2x for medium-term, 1x for long-term. Few ETFs are as universally adaptable to any investment style as index ETFs.

To set a realistic return target, look at the historical annual chart volatility. Volatility differs each year, but you can find the average. Use that average as a baseline, set your target within your risk tolerance, and build a portfolio of matching products.

In my case, I first set an annual average return. For example, with $100K principal targeting 40% annually:

I set monthly targets this way, then review my portfolio each month, adjust strategies, and execute. Each month, I think about what to buy and which strategies to use to hit that number. Some months I hit the target, some months I exceed it, and some months end in the red. But I structure my strategy and portfolio so that the yearly average isn't negative.

Time and Asset Size: The Starting Point of Strategy

Once you know your investment style, risk tolerance, and target return, the last thing to assess is your time horizon and asset size. The larger these two factors are, the more naturally your investing shifts toward lower risk.

If you have time, compounding does the work for you. If you have large assets, there's no reason to take unnecessary risks. When you have both, low-risk investments like dividend stocks and index funds grow your money on their own. If a 20-year-old puts $500/month into an index ETF for 10 years, they invest $60,000; at 10% annual compounding, it becomes roughly $100,000. Hold another 10 years without adding a penny and it grows past $200,000. Time creates compounding, and compounding creates wealth.

Children are the best example. When a child is born, if you create a long-term investment account focused on index ETFs or dividend stocks and contribute even a small amount monthly, you have 18–20 years until they reach adulthood. During this period, parents don't need special effort or time; the market's average returns do the work. $200/month for 20 years means $48,000 invested, but at just 8% annually, it exceeds $100,000. Time does everything; you don't have to.

Conversely, if you want big returns in a short time, you must accept proportionally higher risk. Without time, compounding has no room to work, so you need to boost returns with leverage or concentrate on high-volatility stocks. This is much harder investing. Risk management, stop-loss discipline, and market analysis skills must all be in place to survive. Simply put, you're buying time with money, and the price is risk.

Asset size works the same way. When assets are small, earning 10% doesn't move the needle; you need to be aggressive for meaningful returns. But when assets exceed $1 million, 10% is already $100,000. There's no reason to use leverage anymore. As assets grow, preservation becomes more important, and the allocation to stable investments like dividends and index funds naturally increases.

Ultimately, before choosing an investment strategy, you need to ask: "How much time do I have?" and "How large are my assets?" If you have plenty of both, simple strategies are enough. If you're short on both, your strategy must be precise and you must be prepared to handle the risk.

2. Investment Mindset

One of the most important aspects of investing is mindset. Depending on your investment strategy, there will be moments when you need to endure, and if your mental discipline breaks down, you'll make bad decisions: panic trading, impulse buying, and other mistakes. That's why self-care for your mental state is essential.

This is especially true when you lack a clear basis for decisions, have no stop-loss/take-profit scenarios, or invest without conviction. The longer your investment horizon, the more important consistent mental discipline becomes. Find your own mental care routine or methods that work for you.

The Balance of Optimism and Pessimism: 8 to 2

Optimism changes your life; pessimism protects it. Every crisis in the world stems from overly optimistic interpretation. Here, "pessimism" refers to risk management and crisis management.

When buying stocks, you need to be more optimistic than anyone to buy aggressively. But to protect your money, you must also make negative assessments for risk management at the point of purchase. If you prepare pessimistic scenarios in advance, you can cut losses when those scenarios materialize. Standing still means nothing happens, but moving without thinking causes accidents.

The saying "believe in the stocks you chose" follows the same logic. You need to believe to hold and average down, and as long as the company doesn't get delisted, it can eventually rally for significant gains. Stocks reward larger positions with bigger profits. However, scammers exploit this mentality, so negative assessment should always be done from a risk management perspective.

Personally, I think the right ratio for investing is about optimism 8, pessimism 2. Pessimism is the minimum safeguard for risk management. Companies are the same; too much pessimism prevents forward progress, but only optimism means the brakes don't work and you can't avoid danger.

Information Is Judgment

Information has always been important. Even in an era of information overload, the key is how you produce meaningful information, how you process it, and how you turn it into sound judgment. The process of rapidly collecting, processing, judging, and executing on information is what matters.

Stock charts reflect this information, but the problem is that I only see the price movement; the underlying information and market sentiment that drive the movement reach me slowly, or by the time I learn about them, they've already been priced in.

These days, AI has made gathering information much easier. AI research capabilities can find and present information I didn't even know about. In return, the ability to verify the truthfulness of that information has become even more important. As collecting objective revenue data and catalysts has become easier, it's been tremendously helpful in reading the gap between current market sentiment reflected in the chart and the actual information.

"Don't Think It's Gone Up Enough": Peter Lynch

AI Bubble? Gone Up Enough? Jobs Crisis? Legendary Investor Peter Lynch's Answer | Wall Street Without Gaps

The key question is whether each company's growth story justifies its high multiple. Stocks people call "already risen too much" sometimes multiply several times more from there. "What matters is confirming that the growth idea is actually being executed." You should never easily think "it's risen enough, so it won't go higher."

Apple always had people saying "this is the top," but a few years later the stock would be up 100%, 200%. How much it will rise is determined by the market, not by me.

Recessions and market downturns always happen. People worry about market crashes, but I just focus on the facts that are actually happening and invest accordingly.

So when do you sell? Peter Lynch's sell criterion is "when the growth story is over." You don't sell because the price has gone up a lot; you sell when the very reason the company was growing has disappeared. When revenue growth slows, when competitors steal market share, when the market itself starts shrinking: that's when you sell.

To check if the growth story is still valid, look at a few things. First, if the PEG ratio (P/E ÷ EPS growth rate) is below 1.0, it's still undervalued territory; above 2.0 means overheated. It's also important to check whether EPS growth is maintaining the 15–30% range; growth above 30% is hard to sustain. Then verify whether the expansion pace is accelerating (is this year's revenue or store openings faster than last year's) and whether inventory is piling up faster than sales.

Conversely, signals that the story is over include: slowing expansion, declining quarterly revenue, key executive departures, and two consecutive years of market share decline. When you see these signals, consider selling even if the stock price is still high.

The End of a Trend Cannot Be Predicted

Whether short-term or long-term trading, the hardest thing is trying to predict when an uptrend will continue. Hasty predictions lead to selling stocks that could have gone 100% or 1,000% for a small profit, or conversely, holding after the trend has reversed and taking losses. This simply cannot be predicted.

So it's one of two paths: believe in the stock's future and endure the risk, or trade with small amounts on short-term swings. Neither is easy. Holding with faith in the future is mentally exhausting, and short-term swings can't capture big gains (which invites FOMO), and the trading itself drains your mental energy.

If you can't predict, you can only respond. Take partial profits through split selling while letting the rest ride the trend, or set your own sell scenarios in advance (breaking the 5-day moving average, breaking the weekly low, etc.) and respond mechanically according to those criteria. "Don't predict; respond" is the core principle.

3. Investment Strategy Overview: What Methods Exist?

Once you've assessed your investment style, risk tolerance, target return, and time horizon and asset size, the next step is deciding how to invest. Investment methods can be broadly divided into dividend stocks, index ETFs, individual stocks, and options, each with entirely different risk profiles and characteristics. Where you fall on the investment style spectrum determines which methods you use and in what proportions.

Dividend Stocks (Risk 20–40% | Annual Return 3–15% | Difficulty ★☆☆☆☆)

Dividend stocks are shares of companies that return a portion of their profits to shareholders as cash. The basic strategy is to hold long-term, receive dividends quarterly or annually, and manage your average cost through dollar-cost averaging. The risk-hedging principle combines three elements (dividends + DCA + long-term holding), making it the quintessential conservative investment.

Dividend stocks broadly split into two approaches. One aims for both dividends and capital gains, while the other targets stocks with low monthly volatility but steady dividend payouts, focusing purely on dividend income. To capture capital gains, you need to pick individual dividend stocks with growth potential. For dividend income alone, choose low-volatility stocks or ETFs with stable dividend yields. A prime example is SCHD, a dividend growth ETF that has steadily trended upward on a monthly chart, delivering both dividends and capital appreciation. In contrast, SPYD, a high-dividend ETF, doesn't appreciate much in price but has a high yield, making it suitable for a cash-flow-focused strategy.

The advantage is consistent cash flow. Dividend Aristocrats (companies like JNJ, KO, and PG that have raised dividends for 25+ consecutive years) maintain or even increase dividends during recessions. They offer downside protection in bear markets, and reinvesting dividends creates a compounding effect.

But blindly buying dividend stocks just because you've heard they're "safe" is dangerous. Dividend stocks can still lose principal value when prices fall, and if corporate earnings deteriorate, companies may cut or eliminate dividends entirely. What matters is understanding what the risks of this investment are and how to hedge them. Without that understanding, you won't know how to respond when downturns hit, and you'll only end up stressed.

Realistically, living off dividends alone requires substantial capital. To receive $3,000/month in dividends at a 3–4% yield, you'd need over $1 million pre-tax, or $1.3–1.5 million after tax. Going all-in on dividend strategy with small assets is inefficient.

Index ETF: 1x (Risk 20–40% | Annual Return 10–20% | Difficulty ★☆☆☆☆)

Index ETFs track the entire market. Since you're buying a country's economy, there's no individual company CEO risk, management disputes, or revenue decline risks. The only risk is a market-wide downturn.

In practice, index 1x investing is the market saying "please, just take the money." Just divide your investment into 12 monthly purchases and buy mindlessly, you'll earn the market's average return. The KOSPI's annual high-to-low volatility range is about 40%, and for steadily uptrending indices like the NASDAQ, just averaging down makes it highly likely you won't lose money.

Index investing is mostly approached as long-term, but medium-term annual strategies are also possible. Range-bound indices like the KOSPI have somewhat predictable annual highs and lows, so buying near the bottom and selling near the top can yield 20–40% on an annual basis. Buy in 12 installments throughout the year, sell if it's up at year-end, reset, and start again. Even if you're negative this year, holding another year without selling almost always brings an exit opportunity. The greatest advantage of 1x index is that it requires minimal strategy.

If your target is 10–20% annually with a long-term horizon, 1x index alone is sufficient. Index funds come in various country-specific products (US, Korea, Japan), so you can diversify across country indices without touching individual stocks.

Index ETF: 2x, 3x Leverage (Risk 40–60% | Annual Return 20–60% | Difficulty ★★☆☆☆)

These products track the same index but amplify volatility by 2x or 3x. If a 1x index has 40% annual volatility, 2x becomes 80% and 3x becomes 120%. Gains are bigger, but losses accelerate proportionally.

Like 1x index, 2x can use an annual reset strategy: buy within the year and sell when profitable. For 2x, I believe the return from a single rally within 1–2 years outweighs the management fees. For 3x, the limit is 6–10 months. Long-term holding causes volatility decay (rebalancing drag), where the index returns to its original level but the leveraged product shows a loss. In fact, there's data showing that over a 20-year period where the NASDAQ returned 1,400x, the 3x leveraged product (TQQQ) only returned 50x.

Leveraged ETFs themselves cannot lose more than 100% of your investment. However, since drawdowns are 2–3x those of the underlying index, you can lose most of your principal without a clear stop-loss rule.

The advantage of index leverage is that you can freely adjust strategy regardless of style, using multiplier and holding period. Short-term: 3x, medium-term: 2x, long-term: 1x. You can match the same index to your investment style this way.

Sector ETF (Risk 30–60% | Annual Return 15–50% | Difficulty ★★★☆☆)

Sector ETFs are products that focus on a specific industry or theme. There are ETFs for semiconductors, energy, biotech, shipbuilding, cosmetics, and more. Unlike broad index ETFs that buy a country's entire economy, these bet on the growth of a specific industry.

The risk is higher than index ETFs because the industry itself can fall into recession. While an entire national economy rarely collapses, specific industries can decline for years due to policy changes, technological displacement, or demand reduction. On the flip side, when the industry is booming, returns far exceed those of broad indices.

The advantage is investing in an entire industry without individual stock risk. If semiconductors look promising but you don't know which company to buy, just buy a semiconductor sector ETF. You can participate in the industry's growth without being affected by individual company CEO risks or earnings fluctuations. Diversifying sector ETFs across multiple industries lets you build a portfolio of 5+ positions without any individual stocks.

Sector ETFs also come in 2x and 3x leveraged versions, like a 3x semiconductor sector leverage. Since industry volatility is already higher than broad indices, adding leverage makes the swings extreme. When the industry booms, returns far exceed index leverage, but during industry downturns, they melt just as fast. Sector leverage requires shorter holding periods than index leverage, and you need to be able to read industry cycles.

Individual Stocks (Risk: Varies by Stock | Annual Return -50–100%+ | Difficulty ★★★★☆)

Individual stocks mean investing in a specific company's future value. Potential returns are the highest, but risks vary enormously by stock. A blue-chip like Apple and some unknown small-cap penny stock are both "individual stocks" but carry completely different risk profiles.

Individual stock risks include factors absent from index investing: CEO risk, management disputes, revenue deterioration, market contraction, and even accounting fraud. Since you're putting money into a single company, anything that happens to that company directly impacts your money. That's why you must continuously verify why you're invested in this company and whether its growth story is still valid.

Individual stock investing works on a structure of using fundamentals (company value) to decide what to buy, technical analysis (charts) to decide when to buy, and holding as long as the growth story lives. This requires your own trading strategy and scenarios, making it the area that demands the most study and experience.

Options (Risk 100% | Annual Return -100–unlimited | Difficulty ★★★★★)

Options are the trading of "rights" to buy or sell stock at a specific price. Call options give you the right to buy; put options give you the right to sell. Since they're rights (not obligations), you simply don't exercise if conditions are unfavorable. But the premium you paid for that right is completely lost.

The appeal of options is leverage. A position that would cost $17,500 in actual stock can be taken for under $1,000 with options. If the stock moves as expected, returns of 200%+ are possible. But if the stock stays flat or moves against you, you lose the entire premium. This is why the risk is 100%.

Options have an enemy called time. Theta (Θ), or time decay, erodes the option's value every single day. As expiration approaches, this decay accelerates; so even if you get the direction right, being late on timing means you lose money. Statistics show that 93% of options traders lose money, and the successful 7% are those who fully understand variables like delta, gamma, theta, and vega and have completed at least 3 months of paper trading.

That said, options can be used as hedging tools rather than pure speculation. Buying protective puts on held stocks limits downside risk like insurance, and writing covered calls generates additional income from held positions. But these strategies only make sense when you understand options mechanics. Approaching without understanding is the fastest way to lose money.

Concentrated vs. Diversified Investing

The highest-return structure is going all-in on a single stock, the ultimate high-risk-high-reward play. But that also means one failure can wipe out everything. To reduce risk, split across multiple stocks, set a limit per position, and enter through dollar-cost averaging.

In my case, I've set a per-stock limit of $10,000 and fully invest in a maximum of 10 stocks. Within this framework, even if one stock drops sharply, I can manage the loss relative to my total investment. The ratio of concentration to diversification depends on your investment style and risk tolerance. If you're thrill-seeking, increase concentrated positions; if you're conservative, increase diversification.

Of course, knowing how to deploy both strategies depending on market conditions gives you even more flexibility. For example, in a strong bull market, load up on one or two high-conviction stocks to maximize gains. In an uncertain sideways or bear market, increase the number of stocks and reduce per-stock weighting to spread risk. Over-diversifying in a bull market leaves returns on the table, and over-concentrating in a bear market amplifies losses. Knowing how to adjust the ratio of concentration to diversification based on conditions is the essence of portfolio management.

Summary

No product is inherently good or bad. A portfolio is about selecting and combining products that match your investment style, risk tolerance, and target return. If you're conservative, center your portfolio on dividend stocks and 1x index funds. If you're thrill-seeking, increase the weighting on individual stocks and leverage, but risk management must be rigorous. Detailed strategies and practical execution for each product will be covered in the strategy guide.