The opposite side of an order (usually in relation to a block trade). Essentially, brokers or broker-dealers help market participants to source liquidity (known as contra liquidity) using streams of contra orders. A contra-side order may initiate as an order or a quote. In case the contra-side order is an order (i.e. it is not a quote), the quote will remain active while the order (incoming or resting) will be cancelled. However, in case the contra-side order is a quote (e.g. two quotes submitted by two different trader identities of the same market participant), the trade gets executed.

This order is also known as a contra order.