Trading

In a stock that moves 2% a day, buying 10% of daily volume can cost roughly 0.3% to 0.6% in impact. The guide separates market impact from spread and opportunity cost, shows how implementation shortfall measures all three against the decision price, and applies the square-root rule of thumb (impact ≈ Y × daily volatility × √(order ÷ daily volume)) to a hypothetical $5 million purchase, with a table at 1%, 10% and 25% of volume. It then compares a one-day and a five-day schedule using published coefficients, works through a partially filled order, explains where the models stop being reliable, and ends with a pre-trade checklist.

Losses tend to weigh about twice as much as gains, and the trading records show what that does to returns. Researchers cannot see fear or excitement in a brokerage account, but they can see which positions people sell, how often they trade and when money flows in and out. The guide covers loss aversion, the disposition effect and overconfidence with data from US brokerage accounts, Brazilian and Taiwanese day traders and a 2026 fund-flow study. It shows the recovery math for drawdowns, the break-even win rate for any reward-to-risk ratio, and a 100,000-path simulation comparing a fixed 1% risk rule with doubling the stake after each loss, then lists rules to set before a trade.

A 7% S&P 500 drop halts all US stock and options trading for at least 15 minutes, if it hits before 3:25 pm. That market-wide halt is one of two circuit breakers; the other pauses a single stock for five minutes when its price breaks out of a band set from its own last five minutes of trading. The guide sets out the 7%, 13% and 20% levels with worked trigger points, the 5%, 10% and 20% stock bands, and the reopening auction that decides your fill. It also covers what happens to market, stop and closing orders during a halt, the 10% short-sale rule, what the four halts of March 2020 showed, and the 20% overnight bands due to start with 23-hour trading in December 2026.

A stock sale on Friday, October 9, 2026 settles on Tuesday, because Columbus Day is not a settlement day. Most US stock, ETF and bond trades now settle one business day after the trade, but that single day is counted on a settlement calendar, not a trading calendar, and it decides when a sale's cash can pay for something else, when it can leave the account, and whether a quick resale in a cash account breaks Regulation T. This guide works through computed 2026 dates, including Veterans Day and the New Year boundary, and explains what the 90-day freeze actually restricts, why the dividend ex-date now equals the record date, and why taxes follow the trade date instead.

If a 2-cent spread widens to 20 cents, a round trip on a $10,000 stock position costs $40 instead of $4. Behind that jump sit inventory risk, orders from traders who already know where the price is heading, and quoted size that shrinks even when the spread looks normal. A simple break-even formula shows how these push quotes apart. The guide separates quoted, effective and realized spreads as SEC rules define them, shows how ETFs drifted from their baskets on August 24, 2015 and in March 2020, compares market and limit orders when the offer jumps, and explains why a one-cent tick weighs 100 times more on a $2 stock than on a $200 one, with the half-penny tick now delayed to 2027.

A 200-day average is centered almost 100 trading days in the past, and that lag shapes everything it shows. The guide treats a moving average as what it is, a smoothing filter, and works through the simple, exponential and weighted formulas with their weights shown side by side. Synthetic price series show how many days a 20-, 50- and 200-day average needs to catch up with a jump or a trend, and ten years of S&P 500 closes from FRED show how often the index sat above its 200-day line and when the 50/200 crosses arrived relative to market highs and lows. It closes with what peer-reviewed studies found about moving-average rules, and the checks to run on any backtest.

A margin call is a demand for more equity; on a half-borrowed position a 17% to 33% fall can trigger one. Calls come from Regulation T at purchase, from maintenance requirements as prices move, and, since FINRA's June 2026 rule change, from intraday margin deficits. A hypothetical $20,000 position shows the price fall that starts a call at 25%, 30% and 40% maintenance levels, how much borrowing changes that point, and why a forced sale must be far larger than a cash deposit to cure the same shortfall. The guide also sets out what the SEC's investor bulletin says a firm may do without contacting you and how long the rules allow for meeting each kind of call.

Shares never expire and options do: a $5,000 example shows what that changes for gains, losses and breakeven. Buying a share gives you a slice of a company for as long as you hold it, while buying an option gives you a contract with a strike price, an expiration date and a premium that is gone if the contract finishes out of the money. The article puts the same $5,000 into 100 shares and into 20 call contracts, shows the result at seven stock prices at expiration, prices a protective put on 100 shares, and explains time decay, implied volatility, exercise and assignment, early exercise around dividends, split adjustments and account approval, with the figures labeled hypothetical and the rules tied to the options industry, SEC, FINRA and IRS documents.

In a worked example, a 5,000-share market buy that walks a thin book costs 12.2 basis points. Slippage is the gap between the price you expect when you send an order and the average price you actually receive. This guide works through a hypothetical market buy in dollars and basis points, compares it with a limit order that only partly fills, and shows how a small per-trade cost grows over a year of frequent trading. It also covers what causes slippage (spread, depth, speed, gaps and order size), how it can run in your favor, how market, limit, stop and stop-limit orders trade price certainty against fill certainty, and a short routine for measuring your own fills against an arrival price.

Cashing out $20,000 fast can cost from $5 to $2,000 in spreads and penalties, depending on what you hold. Liquidity is how fast, at what price and at what cost a holding becomes cash, and the answer differs sharply across ETFs, mutual funds, bonds, CDs, I bonds, 401(k) plans, interval funds, homes, financed cars and collectibles. This guide sets out the rule that governs each one, from fund redemption deadlines to early-withdrawal penalties and lien payoffs, then runs a hypothetical $20,000 sale across four holdings with the arithmetic and assumptions shown. It ends with a short checklist for working out your real net proceeds and the slowest step between you and the cash.