From the ASX site: 1. What is the block trade facility? Similar...

From the ASX site:
1. What is the block trade facility?
Similar to the existing exchange-for-physical trading mechanism, ASX’s block trade Facility (BTF) is an entirely off-market – i.e. non-ASX Trade24 – trading facility, enabling ASX 24 participants to bilaterally arrange large volume transactions away from the ASX Trade24 market that might have otherwise negatively impacted normal market quality.
2. Why introduce the BTF?
As capital markets continue to evolve and grow, professional investors are increasingly looking for more efficient ways to transact nominally large orders. It has become clear that that many large investors (particularly OTC and overseas) overlook exchange markets that are not sufficiently deep or liquid enough to enable singularly large trades to be transacted with certainty.
As a result, this business is often transacted elsewhere. In situations where a market is not sufficiently liquid to absorb large orders, non-centrally traded markets (“upstairs” markets) have grown in relevance. In general, upstairs markets have seen increased activity in recent years, principally because they minimise the cost and uncertainty associated with transacting large orders relative to similar transactions in central markets. In addition, upstairs markets afford users greater flexibility in the arrangement and management of orders and in the application of proprietary expertise. In response to this, the BTF was introduced to attract volume to ASX products by offering customers certainty of price and immediacy of execution in the transaction of large orders. The BTF facilitates greater market efficiency through increased liquidity, improved execution quality and lower market transaction costs for large orders. Block trading is not intended to diminish the role of the existing automated trading systems (ASX Trade24), which will continue to be the primary method for trading ASX’s products.