How do stock indices like US30 and NAS100 move?

A stock index measures a basket of shares. US30 is the common trading name for the Dow Jones Industrial Average, 30 large US companies weighted by share price. NAS100 tracks the 100 largest non-financial companies on the Nasdaq and is weighted by size, so a handful of large technology names move it most.

Trading the index means taking a view on the whole market or a sector at once, instead of on one company. One company’s bad news matters less; the broad mood matters more. An index tends to move more smoothly than a single share, but it can still jump when its largest members report or when the whole market reprices.

• The US cash open. The first hour after 09:30 New York time is usually the busiest of the day.
• Earnings season. Results from the largest companies can move NAS100 on their own.
• Rates and inflation. CPI, jobs data and central bank decisions shift what investors pay for future profits, and growth-heavy indices react most.
• Risk sentiment. In a sell-off, indices often fall together and fast.

Outside the cash session, index prices still move on futures trading, but liquidity is thinner and gaps around the open are common.

Many index traders wait out the first 15 minutes after the open, let the opening range form, and then trade a break of it with the stop on the other side.

Indices move in points, and each contract has a dollar value per point. The formula is the same as for any market: size = risk in dollars ÷ (stop in points × value per point).

Worked example, with a hypothetical $1 per point per contract: a $10,000 account risking 0.5% risks $50. A 50-point stop costs $50 per contract, so the size is 1 contract. On NAS100 a 50-point stop can be tight on a busy open, so the right stop may be wider and the size smaller.

MyFundedCapital doesn’t offer index trading yet. None of the programs lists US30, NAS100 or any other index, so read this lesson as general market education: it helps you understand what the US open and the big releases do to the whole market.

If you want US equity exposure today, MFC Stocks trades 1,500+ US stocks in the regular session, with a daily pause of 2% and a maximum loss of 5%. A stock is sized the same way: shares = risk ÷ stop per share.

The index lessons carry over: know when the session is busiest, watch the big US releases, and size from the dollar distance to your stop.