Auction-based Block Trade(A-Blox)

A-Blox was introduced on November 29, 2010 to match block orders with a certain size or more (refer to the table below) from investors wanting to trade anonymously. The orders are concentrated and matched separately from the regular session orders. The execution price is the volume-weighted average price (VWAP) of the issue that is calculated after the market close to be informed to the parties.


The information on the block trading including the order quantity and the execution details are not disclosed throughout the session. The only information disclosed regarding A-Blox trading is whether or not there exits any bid/ask order for each security.

Auction-based Block Trade(A-Blox)
Classification Details
Subject Stock Certificate, ETF, ETN, KDR
Administrative issues and liquidation trading issues are excluded
Trading Hours (Off-hours session) 07:30∼08:30
(Regular session) 09:00~15:00
Execution Method
  • Continuous trading where orders are executed whenever there is a counterparty order
  • Orders are executed according to the time priority in whole amount one by one in the order of receipt time
Execution Price
  • Off-hours session : VWAP1) for the day
  • Regular session : VWAP2) from the matching point until the closing
  • In case where there is not any trade during the regular session, the closing price (or base price if closing prices are not available) is used instead of the VWAP
fn. 1)
VWAP = Total traded value / total number of shares from the beginning to the closing of the regular session
fn. 2)
VWAP = Total traded value / total number of shares from the matching point to the closing of the regular session
Minimum Order Size
  • Minimum order size : KRW 500 million or more (base price x quotation quantity)
  • Trading unit : 100 shares