What are inner and outer volume?

Inner volume trades at the bid (leaning toward sellers taking the initiative) and outer volume trades at the ask (leaning toward buyers). It is only a rough indication.

Updated：2026-11-15

The two terms

Every trade has a buyer and a seller. Look at which side the trade price is closer to:

• Inner volume: trades at the bid, meaning sellers hit the buyers’ orders; usually read as seller-initiated.
• Outer volume: trades at the ask, meaning buyers lift the sellers’ orders; usually read as buyer-initiated.

Inner/outer ratio

Comparing the inner and outer volume over a period gives a rough sense of which side was taking the initiative.

Limits to remember

• Every trade has both a buyer and a seller; inner and outer volume only classify trades by where the price sits against the quotes, which is an estimate.
• Large inner or outer volume does not mean “big players bought or sold”.
• Different data vendors classify and update differently, so the numbers may not match.
• It describes trades that already happened and does not predict later prices.

This article only explains terms. Tenmizu does not provide investment recommendations and this is not investment advice.