Guides
Plain-English explainers with worked numbers — each one hands off to the tool that uses it. Your analysis follows you here too.
The 4% Rule, ExplainedWhat the 4% rule really says, where it came from, why it can fail, and how to test your own safe withdrawal rate.riskMonte Carlo Simulation, ExplainedWhy a single "average return" projection misleads, and how running thousands of randomized futures gives you an honest range instead.riskIs My Portfolio Actually Diversified?Owning ten stocks is not the same as being diversified. What correlation really measures, and how to check whether your holdings are secretly the same bet.riskHow Much Do I Need to Retire?The 25x rule gives you a starting number in five seconds. What actually moves that number takes a bit more work — here is how to find yours.riskSequence-of-Returns Risk, ExplainedTwo retirees can earn the exact same average return over 30 years and end up nowhere near each other — purely because of when the bad years hit.riskWould Your Portfolio Survive a 2008-Style Crash?What stress-testing a portfolio actually means, why drawdown depth and duration both matter, and how to find your real risk tolerance before a crash forces you to.riskRisk Tolerance vs. Risk CapacityTwo different questions people mix up — how much volatility you can stomach, and how much loss your situation can actually absorb — and why the lower one should win.psychologyAsset Allocation by Age (and Why Age Isn’t Enough)The "110 minus your age" rule and its logic — plus the fuller checklist that actually should set your stock/bond mix.portfolioStocks vs. Bonds: What You Actually OwnWhat a share and a bond legally give you, why they move differently in a downturn, and how to split between them for your timeline.fundamentalsHow to Read a Stock’s FundamentalsGrowth, margins, valuation, debt, and cash flow do not mean much alone. Here is how to read them together before you size up a company.fundamentalsIndex Funds vs. ETFs: What Actually DiffersSame index, different wrapper — how index mutual funds and ETFs differ on trading, minimums, taxes, and automatic investing.portfolioDividends vs. Price Growth: The Two Halves of ReturnTotal return is dividend income plus price appreciation. Why mature companies pay and growth companies don't, how reinvested dividends compound, and why a high yield alone is not a reason to buy.fundamentalsVOO vs. VTI: What Actually DiffersVOO tracks the S&P 500, VTI tracks nearly the whole US market — here is what that difference actually means for your portfolio.portfolioThe 60/40 Portfolio, ExplainedWhy 60% stocks and 40% bonds became the default "balanced" portfolio, how it has actually behaved, and what 2022 exposed about its limits.portfolioThe Efficient Frontier, ExplainedWhy mixing imperfectly-correlated assets can beat holding either alone, what the frontier curve actually shows, and why the "optimal" portfolio is harder to find than it looks.portfolioLazy Portfolios, ExplainedThe case for owning a handful of broad index funds and leaving them alone — plus how to choose between a two-fund, three-fund, or all-in-one approach.portfolioPortfolio Rebalancing, ExplainedWhy your allocation drifts away from your target over time, why that quietly changes your risk, and the simple rules people use to reset it.portfolioFactor Investing, ExplainedWhat a "factor" actually is, the well-known ones — size, value, momentum, quality, low volatility — and why none of them are guaranteed to keep paying.portfolioThe Sharpe Ratio, ExplainedWhat the Sharpe ratio measures, a worked example comparing two portfolios, the rule-of-thumb bands people cite, and where the math breaks down.riskShould You Invest Internationally?Most investors hold far more of their own country’s stock market than its size justifies. What home-country bias is, why it happens, and the honest case on both sides.portfolioHow to Backtest a Portfolio (and Its Limits)What backtesting actually measures, how to read CAGR, drawdown, and Sharpe, and why one historical path is a narrower test than it looks.portfolioWhat Is a P/E Ratio?The P/E ratio tells you what the market charges for a dollar of profit. See how it works, why context is everything, and the traps that quietly distort it.fundamentalsWhat Is EPS (Earnings Per Share)?Net income divided by shares — but which shares, and whose income? Basic vs diluted, GAAP vs adjusted, and the buyback effect, explained in plain English.fundamentalsWhat Is Market Cap?Price times shares outstanding — the real size of a company. Why a $10 stock can dwarf a $500 stock, and what small, mid, and mega cap actually imply.fundamentalsWhat Is Stock Float?Float is the slice of a company’s shares that actually trades. Learn why small floats turn ordinary news into violent moves — in both directions.fundamentalsWhat Is Short Interest?What short interest and days to cover actually measure, where the twice-monthly data comes from, and why heavy shorting cuts both ways.fundamentalsRSI, Explained: What the Relative Strength Index Actually MeasuresRSI squeezes recent gains and losses into a 0-100 momentum score. What 70/30 really mean, why strong trends break the rule, and how divergence works.technicalsMACD, Explained in Plain EnglishMACD turns the gap between two moving averages into a momentum gauge. What its three parts mean, how crossovers work, and why it lags in choppy markets.technicalsMoving Averages, Explained in Plain EnglishA moving average smooths price into one trend line. Learn SMA vs EMA, the 20/50/200 lines, golden crosses, and where these tools quietly fail.technicalsR-Multiples and Expectancy: The Math Backbone of TradingMeasure every trade in units of planned risk, then combine win rate and average win into one number: expectancy. The math backbone of any trading system.riskThe Wash Sale Rule, ExplainedSell at a loss and rebuy within 30 days, and the IRS presses pause on your deduction. How the 61-day window works and where the loss goes, in plain English.taxDollar-Cost Averaging, ExplainedFixed dollars buy more shares when prices drop. The harmonic-mean math behind DCA, the honest lump-sum research, and when averaging in actually fits.psychologyWhat Is Position Sizing?Account times risk percent, divided by per-share risk. The fixed-fractional method worked start to finish, plus the correlation trap hiding inside it.riskHow Stock Splits WorkShares multiply, price divides, value stays put. The 4:1 mechanics, why companies split, what a reverse split signals, and the evidence on split pops.fundamentalsUnderstanding Drawdowns: The Math of Losing and RecoveringA 25% drawdown needs a 33.3% gain to recover, and a 50% drawdown needs 100%. The math of losing streaks, and how to size so yours is survivable.riskHow Short Selling Works: Borrow, Sell, RebuyBorrow shares, sell them, buy them back cheaper. The mechanics step by step, the fees, the margin math, and why losses on a short have no ceiling.riskWhat Is Beta? The Slope That Measures Market ExposureBeta is the regression slope of a stock's returns against the market. What 0.5, 1.0, and 2.0 mean in a real selloff, and where the number quietly breaks.riskWhat Is EBITDA?EBITDA strips interest, taxes, depreciation, and amortization out of earnings. See how it is built, why analysts lean on it, and where it flatters.fundamentalsFree Cash Flow ExplainedFree cash flow is the cash left after a business pays to maintain and grow itself. The formula, FCF yield, the stock-comp catch, and why DCF starts here.fundamentalsReturn on Equity (ROE) ExplainedROE shows how much profit a company earns on each dollar of shareholder capital. The formula, what counts as good, and how debt can fake a great number.fundamentalsSupport and Resistance: Why Price Remembers Old LevelsLevels form where trapped traders and resting orders pile up. How to draw zones honestly, why broken levels flip roles, and how false breaks punish chasers.technicalsImplied Volatility: The Move the Options Market Is Paying ForIV is the size of move option prices already assume. IV vs realized vol, rank vs percentile, the straddle-implied move, and the earnings crush, with math.technicalsOptions Greeks: Delta, Gamma, Theta, and Vega Through One TradeDelta, gamma, theta, and vega tracked through a single $100 call: what each Greek pays or costs in dollars, and why everything accelerates near expiry.technicalsDividend Yield and Payout RatioYield is the dividend divided by the price, which is exactly why a crashing stock suddenly yields 10%. How payout ratios separate safe dividends from traps.fundamentalsReading an Income StatementOne realistic income statement walked line by line, from $1.2B of revenue to $0.79 of EPS, with the margin at each stage and the games played below the surface.fundamentalsWhat Is a 13F?The quarterly filing where $100M+ managers reveal their long US stock positions, 45 days late. What a 13F shows, what it hides, and how to read the changes.fundamentals