For: beginners buying US stocks + broad-market ETFs (VOO / QQQ).

How to use this: You don’t need to read it all at once. Come back and look things up when you hit a term you don’t know. The ⭐ items are the core concepts to master first; the rest you can fill in gradually. Each entry roughly follows: what it is → how to use it → normal range / common pitfalls.

The basics: the asset classes you can buy

Stock / Equity ⭐ A small slice of ownership in a company. Holding it gives you a small claim on the company’s future profits. What it’s worth in the long run ultimately depends on how much the company can earn.

ETF / Index Fund ⭐ An ETF (“exchange-traded fund”) trades like a stock — you can buy and sell it any time. An index fund is the most common kind: it doesn’t pick stocks, it just mechanically holds a basket of assets in proportion to a “list” (an index). Buy VOO and you own a tiny slice of each of the ~500 companies in the S&P 500; buy QQQ and you hold the ~100 names in the Nasdaq-100 (tech-heavy). The upside is diversification and low cost.

Bond Essentially “you lend money to a government or company, it pays you interest periodically and returns the principal at maturity.” Steadier than stocks, and usually lower-returning. When interest rates rise, the price of already-issued bonds falls (many people don’t know this).

Cash / Money Market The safest, barely volatile — but inflation slowly erodes its purchasing power over time. Its role isn’t to earn money, it’s to be your “ammunition” and “cushion.”

Reading a stock’s key metrics (valuation)

Market Cap ⭐ A company’s total price tag = share price × total shares. Whether a company is “big” is judged by market cap, not share price. Common tiers: large-cap (>$10B), mid-cap, small-cap.

Share price ≠ cheap or expensive (a key misconception) ⭐ A $500 stock isn’t necessarily “more expensive” than a $50 one. Share price is just “total value ÷ number of shares” — it has no direct relationship to whether the company is over- or undervalued. To judge cheap vs expensive, look at the valuation multiples below (like P/E), not the per-share price.

EPS (Earnings Per Share) Net income ÷ total shares — “how much profit each share gets.” It’s the denominator of the P/E ratio and one of the most-watched numbers each earnings season.

P/E Ratio ⭐ = Share price ÷ earnings per share. Intuitively: at the current level of earnings, how many years it takes to “earn back” the price you paid. A high P/E usually means the market expects fast future growth (or it may be overvalued); a low P/E may be cheap, or may signal the market isn’t optimistic.

  • TTM P/E: uses the actual profit of the past 12 months (looking back).
  • Forward P/E: uses forecast future profit (looking ahead).
  • Reference: the S&P 500’s long-run historical average is roughly 15–20x.

PEG Ratio = P/E ÷ earnings growth rate. Used to correct for “is a high P/E actually expensive or reasonable?” Rule of thumb: around 1 is reasonable, well above 1 may be pricey. (A rough indicator Peter Lynch favored — don’t treat it as an exact formula.)

P/B (Price-to-Book) = Share price ÷ book value per share. More meaningful for “asset-heavy” businesses like banks and real estate; of little reference value for asset-light tech companies.

P/S (Price-to-Sales) = Market cap ÷ revenue. Often used for growth companies that aren’t profitable yet (with no profit, you can’t compute a P/E).

Dividend Yield = Annual dividend per share ÷ share price. E.g. a $100 stock paying $3 a year yields 3%. Note: an absurdly high yield is sometimes an illusion created by a crashing price — not necessarily a good thing.

Revenue / Net Income Revenue is “how much was sold” (top line); net income is “what’s actually earned at the end” (after all costs, expenses and taxes). Be wary of companies whose revenue grows fast but never turn a profit.

Free Cash Flow (FCF) ⭐ = Cash generated by operations − the capital spending needed to maintain/expand. In plain terms, “the cash the company can truly spend freely.” Profit can be dressed up with accounting; cash flow is harder to fake, so many veterans weight it more heavily.

ROE (Return on Equity) = Net income ÷ shareholders’ equity. Measures “for every $1 shareholders put in, how much the company earns in a year” — a key gauge of profit efficiency. Consistently 15%+ over the long run is usually considered excellent.

Margins Gross margin = (revenue − cost) ÷ revenue; net margin = net income ÷ revenue. High and stable margins often indicate a “moat” (strong pricing power, little competition).

Reading an ETF / fund’s metrics

Expense Ratio ⭐ The annual management fee a fund takes from the assets you hold, as a percentage. It looks tiny, but its impact under long-term compounding is huge.

  • VOO is about 0.03%/yr, QQQ about 0.20%/yr.
  • Intuition: a 1% annual fee can erode more than a fifth of your final return over 30 years. This is the first number to check when choosing a fund.

AUM (Assets Under Management) The total assets a fund manages. Very small funds risk being closed down; mainstream broad-market funds (VOO / QQQ) are enormous, so no worries there.

Holdings & Weights Exactly which companies a fund holds and at what proportions. Before buying, glance at the top-10 holdings — you’ll find many “different” tech ETFs have heavily overlapping top-10 holdings (the same few mega-caps), so buying several may not actually diversify you.

Tracking Error The deviation between an index fund’s actual performance and the index it tracks. Smaller is better — it means the fund “replicates” more precisely.

Premium / Discount The gap between an ETF’s market price and its actual net asset value (NAV). Mainstream large ETFs hug their NAV; niche, obscure, or off-hours ETFs can show a clear premium/discount — effectively paying more / receiving less.

Liquidity / Volume How much it trades each day. Good liquidity = small bid-ask spread, easy to fill; with an illiquid niche ETF, the spread alone can eat a meaningful chunk of your return.

Distribution An ETF periodically passes the dividends its holdings pay through to you. VOO-type funds have a certain dividend; QQQ less so (growth stocks generally pay little).

Return and risk metrics (what decides whether you sleep at night)

CAGR (Compound Annual Growth Rate) ⭐ Converts the total growth over a period into “the average compound growth per year.” It’s a geometric mean, not a simple “total return ÷ number of years” — the latter overstates it. E.g. up 60% over three years is a CAGR of about 17%, not 20%. (Why too high? Compounding: 20% a year would actually compound to +73% over three years, far past 60%; to land exactly on 60% you only need ~17% a year.) Why it matters: it compresses bumpy multi-year performance into one comparable annualized figure — the universal yardstick for comparing the long-term performance of different funds/strategies.

Total Return vs Price Return ⭐ Price return only counts how much the price/NAV rose; total return also includes the dividends received (assumed reinvested). Over the long run the gap is large — a substantial part of the S&P 500’s long-term return comes from reinvested dividends. When looking at a fund’s or index’s historical performance, look for the “Total Return” figure and don’t be misled by numbers that show price appreciation only.

Volatility ⭐ How violently the price swings up and down, usually measured by standard deviation. High volatility ≠ certain loss, but it means a bumpier ride that tests your nerves more. QQQ’s volatility is clearly higher than VOO’s.

Beta (β) ⭐ Measures how much an asset amplifies the swings of the whole market. The market itself = 1.0.

  • β > 1: swings more than the market (e.g. many tech stocks, QQQ).
  • β < 1: steadier than the market (e.g. utility stocks).
  • β ≈ 1: moves in step with the market (VOO is close to 1).

Max Drawdown ⭐ The largest historical drop from a peak to a trough. It’s the key gauge of “how much pain you’d have to endure in the worst case.” A max drawdown of 50% means you might have to watch your account get cut in half. Check an asset’s historical max drawdown before buying, and ask yourself whether you can stomach it.

Sharpe Ratio = (return − risk-free rate) ÷ volatility. Measures “how much excess return you get for each unit of risk you take on.” Higher is better — a common way to compare the “bang for the buck” of different strategies.

Correlation ⭐ Whether two assets rise and fall together, ranging from −1 to +1.

  • Near +1: highly synchronized (e.g. VOO and QQQ, both US stocks, rising and falling together).
  • Near 0 or negative: independent or even opposite movements.
  • Real diversification comes from holding assets with low correlation. Holding VOO + QQQ together — highly correlated — gives limited diversification.

Trading and costs (quietly eating your money every day)

Bid-Ask Spread ⭐ The gap between the buy price (bid) and the sell price (ask). That little slice where you’re “down the moment you buy” is the spread. For mainstream large stocks/ETFs it’s tiny; for obscure names it can be large.

Market vs Limit Order ⭐

  • Market order: fills immediately at the current best price — fast, but the price isn’t under your control (in thin liquidity it can fill at a terrible price).
  • Limit order: you specify a price and it only fills at that price — price is controlled, but it may not fill.
  • Beginner habit: unless you urgently need to fill, prefer limit orders.

Slippage The gap between the price you expected and the price you actually got, common with large orders, sharp volatility, or thin liquidity.

Tax ⭐ An often-overlooked layer of cost. When you sell and realize a gain you usually owe capital gains tax, and dividends received may be withheld too. The general rule is the longer you hold, the friendlier the rate (many markets reward long-term holding), so frequent trading costs you not just spread and slippage but extra tax. Exact rates depend on your jurisdiction and account type — figure out your own tax situation before you start, because the impact on your take-home return is often bigger than you’d think.

Portfolio and strategy (the layer that matters most) ⭐

Asset Allocation ⭐ How your money is split across stocks / bonds / cash. Research repeatedly shows: what mainly determines your long-term return and volatility is the allocation, not which individual stock you picked. This is the layer beginners should care about most yet most easily ignore.

Diversification ⭐ “Don’t put all your eggs in one basket.” By holding multiple, low-correlation assets, you reduce the damage any single blow-up does to you. Note: buying a pile of highly correlated things (like several tech ETFs) is not real diversification.

Compounding ⭐ Returns generating further returns, like a snowball. Its power comes from time — at the same annual return, the final result over 30 years vs 10 years is worlds apart.

Shortcut: the Rule of 72. Divide 72 by your annual return rate to estimate the years needed to double your principal. At 8% a year, ~9 years to double; at 4%, ~18 years. A handy tool for mentally gauging the power of compounding.

Dollar-Cost Averaging (DCA) ⭐ Investing a fixed amount at fixed intervals (e.g. buying a chunk of VOO every month), without trying to predict highs and lows. The benefit is averaging out your cost, avoiding “going all-in at the top,” and not letting emotion drive your timing.

Rebalancing After a while, the assets that rose most grow as a share of your portfolio, drifting away from your target allocation. Rebalancing means periodically selling a bit of what rose and topping up what lagged, pulling the proportions back to target. In essence, “passively selling high and buying low.”

Position Sizing How large a single asset is in your portfolio. However bullish you are on something, cap any single holding so that if it blows up it can’t drag down the whole.

Macro factors (the tide that moves the whole market)

Interest Rates / The Fed ⭐ The benchmark rate the Fed adjusts is one of the biggest variables affecting the stock market. Rough rule: hiking (money gets more expensive) is usually bearish for stocks, hitting growth/tech (QQQ) hardest; cutting is usually bullish. Because rates affect “what future money is worth discounted to today.”

Inflation / CPI ⭐ How fast prices rise, usually measured by CPI. Too-high inflation forces the Fed to hike, which then suppresses stocks. The market is very sensitive to the monthly CPI print.

Don’t forget to compute the real return. Nominal return is the headline number; real return ≈ nominal return − inflation. If you made 5% in a year but inflation was 4%, your purchasing power actually grew only ~1%. To gauge whether an investment truly made you richer, look at the real return, not the headline.

Yield Curve The curve connecting the rates of government bonds of different maturities. When short-term rates exceed long-term (“inversion”), it’s often seen as an early warning of recession.

Dollar Index (DXY) The strength of the US dollar against a basket of currencies. A strengthening dollar often pressures emerging markets and commodities.

Leverage and derivatives (high risk — understand before you touch)

Margin ⭐ Borrowing from your broker to amplify your buying. It magnifies gains and losses; when losses get too big it triggers a “margin call / forced liquidation,” potentially selling you out at the very bottom. Use with caution as a beginner.

Leveraged / Inverse ETF Decay ⭐ Products like TQQQ (3x long the Nasdaq) and SQQQ (3x short) target a fixed multiple of daily return. Because they re-lever every day, choppy back-and-forth markets create “volatility decay” — holding long term often underperforms the target you imagined, and you can lose even when the direction was right. They’re designed for short-term hedging/trading, not for buy-and-hold.

Options Contracts that give you the right to buy/sell an asset at a certain price (call / put). Usable for hedging or speculation — high leverage, complex mechanics. Strongly recommended to nail down all the basics above before touching them.

One-paragraph summary for beginners

First, thoroughly understand the “Portfolio and strategy” section, plus the metrics expense ratio, max drawdown, correlation, and CAGR. Their impact on your long-term outcome far outweighs studying any single individual stock. Treat these as the “foundation,” and the rest of the terms as tools you look up when you need them.

Disclaimer: this article is conceptual education and does not constitute investment advice.