Index Trading Guide: US30, US100 and Event Days

An index is not a thing you can buy. It is a number computed from hundreds of stock prices, and everything tradable around it, futures, CFDs, funds, is a derivative of that number. Understanding that one remove explains most of the oddities index traders run into.

What an index price actually is

An index tracks a basket of stocks combined by a weighting rule. The S&P 500 (US500 on most CFD platforms) weights 500 large companies by market value. The Nasdaq-100 (US100) does the same for 100 large non-financial names and ends up dominated by technology. The Dow (US30) is the odd one out: it weights its 30 companies by share price, so a $500 stock moves the index more than a company twice its size trading at $150.

Weighting is why the three "US market" indices diverge. A tech selloff hits US100 hardest, while a single expensive Dow component's bad day can dent US30 while US500 barely notices.

Cash hours versus derivative hours

The cash index is only computed while US stocks actually trade, 9:30am to 4pm New York time. Outside those hours your index CFD keeps quoting because it prices off index futures, which trade nearly 23 hours a day.

Practical consequences:

• The CFD trades overnight even though the index itself is frozen. The overnight price is the futures market's live estimate of where the cash index will reopen.
• The cash chart gaps at 9:30am; the futures-based chart usually does not, except across the weekend, when everything gaps together at the Sunday reopen.
• News at 3am moves your position while the stocks inside the index have no prices at all. Liquidity then is a fraction of the regular session, so stops fill worse.

Event days: CPI and FOMC

Two scheduled releases dominate the index calendar. CPI lands at 8:30am New York time, an hour before the cash open, so the entire first reaction happens in futures and CFDs on thin pre-open books. Fed decisions land at 2pm with a press conference at 2:30pm, mid-session, and routinely produce a two-wave reaction: one on the statement, another, often opposite, while the chair speaks.

On both, spreads widen and price whips through both sides of the pre-event range before choosing direction. A stop placed for normal conditions is a coin flip in those first minutes. Standing aside through the release, or trading only the aftermath at reduced size, is a position too, and often the best one. The session-picking habit transfers from FX directly; the framework in forex sessions and when to trade applies with the clock shifted to equities.

The personalities

The trap in this table is the point illusion. US30 trades at a much higher index level than US100, so a 300 point drop in each is a completely different percentage event. Compare indices in percent, and size positions in percent of account, never in points. Note also that the three are heavily correlated: long all three at once is one trade in triplicate, not diversification.

Running indices on a funded account

Percentage thinking is what connects index behavior to account rules. US100 can swing more than a percent in an ordinary session, so a position's notional must be sized so that a routine swing does not consume the day's loss allowance, and event days deserve half size or none. Indices sit alongside FX, metals and crypto on the FFUNDED instrument list, on accounts that are simulated with virtual capital and pay out real money. The habits that carry traders through evaluations elsewhere, patience and fixed risk per trade, transfer to indices unchanged; how to pass a prop firm challenge covers them in full.

Frequently asked questions

Why does my index CFD move when the stock market is closed?

Because it prices off index futures, which trade nearly 23 hours a day, while the cash index is only calculated during US stock hours, 9:30am to 4pm New York time. Overnight, the CFD reflects the futures market's live estimate of the next cash open.

What is the difference between US30, US100 and US500?

US30 tracks 30 blue-chip stocks weighted by share price, US500 tracks 500 large companies weighted by market value, and US100 tracks 100 large Nasdaq non-financial companies with a heavy technology tilt. They are strongly correlated but differ in speed, with US100 usually the fastest mover in percentage terms.

Should I trade indices during CPI or FOMC?

The first minutes after the release are the most treacherous: spreads widen and price frequently sweeps both sides of the range before trending. Many experienced traders stand aside for the release itself and trade the aftermath at reduced size once direction and spreads settle.

Do index CFDs expire like futures?

No. Cash index CFDs are open-ended and simply accrue overnight financing, while the futures they price from expire quarterly and get rolled. That makes CFDs simpler for multi-day holds, at the cost of nightly financing charges.