The depth of market (DOM, or order book) shows the limit orders waiting at each price. The tape (time and sales) shows every trade as it happens. Together they are the rawest view of the market there is, and the hardest to read well.
The DOM
Bids (buy limit orders) sit below the current price and asks (sell limit orders) above it, with the size waiting at each level. Traders watch for large resting orders that might act as short-term support or resistance, and for orders being added or pulled as price approaches.
What it can't tell you
- Orders can be cancelled. A large bid can vanish just before price reaches it.
- Icebergs hide size. An iceberg order shows a small quantity but keeps refilling as it trades, revealing its real size only on the tape.
- Spoofing exists. Placing orders you intend to cancel to mislead others is illegal in regulated markets, but it still happens.
The tape
Time and sales lists each trade: time, price, size, and whether it traded at the bid or the ask. Tape readers watch for large prints, bursts of speed, and whether aggressive orders are actually moving price.
| What you see | Common reading |
|---|---|
| Large offer on the DOM, tape keeps buying into it, price doesn't move | The offer is absorbing buyers; if it holds, price may drop |
| Large offer gets traded through, then price speeds up | Absorption over; breakout fuel |
| Same price keeps trading with small size shown on the DOM | Likely an iceberg order |
| Large bid pulled as price approaches | Possible spoof; don't trust it as support |
Key takeaways
- The DOM shows resting limit orders at each price; the tape shows every trade as it happens.
- Large resting orders can act as short-term barriers, but they can be cancelled or be spoofs.
- Icebergs reveal their true size only on the tape, as the same price keeps trading.
- Watch whether aggressive orders move price or get absorbed at a level.