Beginners

How to Understand a Market Quote

Astron Team · 09/24/2026 · 4 min read

Before learning any indicator or strategy, there's a more basic skill that tends to get skipped: knowing how to read the numbers that show up on a quote. For beginners, a screen full of flashing values can look more confusing than it really is — most of that information follows a simple pattern, once you understand what each field represents.

Bid and ask: the two sides of every price

Every traded asset actually has two prices at the same time, not just one:

• Bid: the highest price someone is willing to pay for the asset at that moment.
• Ask: the lowest price someone is willing to sell the asset for at that moment.

When you buy at market, you pay the ask price. When you sell at market, you receive the bid price. That means if you bought and sold immediately in sequence, with no price change in between, you'd already have a small loss — the difference between the two prices.

What the spread is

This difference between bid and ask is called the spread, and it works as a built-in cost on every trade. An example: if an asset's bid is R$ 24.80 and its ask is R$ 24.84, the spread is R$ 0.04. On a trade of 100 units, that represents a R$ 4.00 difference between buying and selling at the same instant.

More heavily traded assets, with more people buying and selling all the time, usually have a smaller spread. Less liquid assets, or ones traded outside regular hours, tend to have a wider spread — one of the reasons trading during low-liquidity hours usually costs more per trade.

Last price, high, low, and open

Besides bid and ask, most quotes show four other reference numbers:

• Last price: the price of the most recently closed trade, not always the same as the bid or ask the next instant.
• Open: the first price traded in the period being analyzed (day, week, month).
• High and low: the highest and lowest values traded within that same period.

Comparing the last price with the open shows whether the asset has been rising or falling since the start of the period. Comparing the last price with the high and low shows where it sits within that day's trading range — similar information to what the Stochastic Oscillator calculates automatically.

Percentage change: the number everyone looks at first

Percentage change shows how much the price has moved from a reference point, usually the previous period's close. The formula is simple:

% Change = ((Current price − Reference price) ÷ Reference price) × 100

Example: if an asset closed the previous session at R$ 50.00 and is now trading at R$ 51.50, the change would be: ((51.50 − 50.00) ÷ 50.00) × 100 = (1.50 ÷ 50.00) × 100 = 3%. A drop to R$ 48.50 in the same scenario would result in a change of -3%, using the same math with the sign flipped.

Volume: how many trades back that price

Volume shows the number of units traded in a given period. A price move accompanied by above-average volume tends to carry more conviction than the same move on low volume, since it reflects more participants agreeing with that new price level.

Putting the numbers together into a reading

A complete quote tells a small story: where the price started (open), how far it reached at both extremes (high and low), where it stands now relative to those extremes, how much it changed percentage-wise, and with how much trading volume behind it. Learning to read these numbers together, instead of looking only at the current price in isolation, is the first step before any more advanced analysis — and it's worth remembering that, in any real trade, the spread between bid and ask is a cost that needs to be factored in from the start.

Over time, reading a full quote stops being a conscious exercise and starts happening almost automatically, the same way reading the time on an analog clock does. Until then, it's worth the habit of checking each of these numbers before deciding anything, instead of just reacting to the price flashing on the screen.